Only my second date.  

My number is 12 minutes. How I arrived at that I'm not sure; but I know that if they are 10 minutes late with no communication, I start getting pissed. (All they need to do is make a call.) Two more minutes and I'm out of there.  

I'm more willing to wait if she's being communicative. Otherwise about 10-15min after scheduled time and I'm moving on with my day. As for being "back to back" like that, it kinda kills the mood for me knowing that. And makes me think she'll rush me out the door.

I dont leave my house without a room #. There is no reason why you cant have the room # as long as you agree that you wont show up unannounced or until given the green light

you waited 10 minutes longer than I would have.  After 20 minutes, if I don't hear anything, I will leave and not look back, but if l get a text with a reasonable explanation AND an estimate of how much longer I have to wait.  If I don't have to be somewhere, I will usually stay if it's not more than 10-15 minutes longer.  For me communication is the key.  If they are running 30 minutes late, and don't call or text to tell me.  they will never hear from me again, and I will be patting myself on the back all the way home for not giving deposits.  

First, another explanation that I've heard about. Sometimes, someone is already in the room and asks for an extension. A bird in the hand is worth two in the bush, and if she's having a good time, the hostess will agree to the extra 30 min or hour from the guy already in hand (or mouth or other place).  
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You might think that the hostess could make up an excuse and say to her guest. "I was supposed to meet my girl friend for dinner. Or was it to go to a club?  Or a movie?  Whatever, I'd love to have you stay, but please excuse me for 2 minutes to give her a call and explain that I'll be delayed so she doesn't worry about me and call the cops on us." whereupon she goes into the bathroom and calls YOU to APOLOGIZE and to ask if you can come by later.  
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(Some or even many Providers have a safety person they check in with before and after a meeting. If she goes overtime and doesn't call, the safety person might alert hotel management or even the cops.)  
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How long would I wait? 30 min.  
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My first NCNS (by a well reviewed Provider), I was really worried that something was wrong (cops, mugged, etc.) and started calling her assistant many times (t -5 min for the room #, t=0 t+5 t+10 t+20  t+30 t+45 t+60) for an hour. Her assistant was very nice but working at her own job (bartender) to take my calls and to try to reach my hostess.  I left after an hour.  
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Since then, there have been occasional but COMMUNICATED delays ("Sorry, she's a running a little late. 10 min OK?" "... another 10 min OK?" but usually keeps things reasonable: 20-30 min, tops. My last NCNS? 30 minutes. I emailed the booker (all email; no phone or text; worked for me several times but not this time) when I arrived 15 min early and got a reply. t -5, I asked for room number; no reply; t=0, sent another email, no reply; t +10, email, no reply; I left after sending an explanatory email at t+30.  
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Providers: find an excuse and call the guy! A call and cancel (or delay) is better than NCNS.  
Time to wait for an NCNS in progress to call before leaving: 30 minutes.

That is a good point concerning deposits. I’ve always read, ‘don’t go to a provider requiring a deposit’.  

I just go do something else if she is running late..  While in Vegas couple of yrs ago, I was waiting on a gal, and she said she is stuck due to the Rock n Roll marathon.  I was staying in Downtown and there were lot of road closures because of the event..  So we moved our 8:00 P.M. to 10:00 P.M.  I went downstairs, put about $100 on Video Poker and came came back with over $300.. Did well that night..  I can be flexible as long as she is in touch with me and communicates. If she ghosts me, then forget about it !  

It doesn't work like that for guys, sweetheart !  

While I've gotten hotel info anywhere from two days prior to the morning of the appointment, I have NEVER gotten the room number prior to actual arrival in the hotel/incall parking lot.

My time is as valuable as anyone's. If a lady is more then 15 minutes late without contacting me it is likely she doesn't respect me or my time. I don't do this to them. I don't put up with bullshit. Things happen but in an era of cell phones it is just rude not to communicate delays.

I have two providers who I seen regularly over several years and I would wait a hour or more for them. At that point we both have a long history of being on time and not canceling. For new providers I am in the 15 minute school of thought and hopefully less. I try to stick with well reviewed P-411 providers and avoid the BS

The question of how long to wait seems to be well discussed here. And I agree that generally, if she's communicating consistently, my tolerance for waiting is longer.    Life happens, and as long as a 30-minuite flex window can work both ways, I can deal with it.  But leaving me hanging with no response - that's a total fail and I'm gone after 15 minutes and won't rebook without a very convincing apology and explanation.  

I am outcall only in my homebase Vegas and like you I am not leaving home to go to the strip without the room#.
When I am touring I am incall only and there is no way I am giving a guy my room# when I give him the location 1hr-90min in advance of appt time.
I've had guys show up to location an hour plus ahead of time. A guy who just knows my location shows up that early is really indiscreet. I wonder what he would do if he had my room# as well?
Guys do not get my room# until they have called or text they have arrived at my hotel.  
Just my .02

One of the main reasons I see providers is that I'm busy and don't have much time these days for personal relationships. I book based on my availability, not hers. So if a provider is late it means sessions run short for me because I usually already have other things lined up after. I typically arrive 10 mins early and let them know I have arrived for when they're ready. No communication and I'll leave 5 mins after meet time. With communication I'll be willing to wait 15 minutes.

Did you show up early..?

As a provider, I tell all clients that if they are late then they will have to wait until I am able to fit them in (I don't care what the reason is). I explain to them that it cuts into me making money and that either they can wait or I'll charge more.

It is an assumption, certainly. However, all other or at least all I can think of, would allow her to reply. If she’s hanging by her toes, ignoring her patron, that’s even worse.  

If you drove 20 minutes to her hotel & waited 30 minutes you have wasted enough of your time. She does not respect you, or appreciate your business. Poor communication & lack of professional courtesy you leave immediately. I would not wait for a potential client that long. Bad energy & you haven’t even met yet no bueno. The provider should have responded before your appointment time. Choose wisely.

If  I arrive at the agreed upon time and text her letting her know, and she communicates that she needs a few more minutes, then no problem, I can wait for up to 15 minutes. If it's going to take longer than that I'll leave, otherwise I start getting paranoid sitting in the lot. Once a woman texted and said she was having an issue and she needed 30 minutes, so I left and came back then.

This is never an issue with P411 ladies.  I always confirm the day before and the morning of.   Pretty much the same with ladies who have several TER reviews.  However women I have contacted through bottom feeder sites are the ones who will keep you sitting in your vehicle as you await their text in the parking lot of the Motel 6.  I have steered away from that for the most part!

It  depends on the situation. If I get replies back asking me to wait for a few minutes then ok. The longest I waited was 25 minutes, but there was a mixup and 2 girls were sharing  the room.  If I don't get a reply after 5-10 minutes, and it's happened only once, then I send a "I'm leaving" message and cross her off my "to see" list.

Most women are narcissistic and it takes a lot of self control to act professionally against their natural impulses. They don't care about you and never will. However a few manage to restrain themselves enough to establish a professional reputation in order to make a living. But even they slip back into I'm a princess mode from time to time. You have to wait? Sucks to be you.

He's not entirely incorrect.  

If Johnny Deep wasn't good enough for Amber Heard, imagine your ranking in women who regard you as a complete stranger, let along a significant other.

She was P411, through which I contacted her.

This woman was a P411 veteran.

Sometimes I'm running late and in that case I always text or email the gentleman to let him know I'm running late and why. And I always give an ETA. If she was giving you the run around and changing the time, it sounds like she was booked up and her date before yours went on longer than she thought.  

Agreed. For me, it depends on the responsiveness. A couple of times a provider has texted me a few hours before our time asking to push the time back an hour or so, and once when one said she could meet me earlier than planned, if I was able. But when I arrive as planned, text for the details, and they go radio-silent on me, that can be a different story. Since I only see those with are well-established and with good reputations, my chances of being stood up are small.