I recently saw a well-reviewed provider who was still on her cycle.  Had i known i would not have seen her, as for me this is a major turn off.  How have others, both hobbyists and providers alike, handled this??

was a provider who got her period during out session.  She was embarrassed and profusely apologized.  In your situation, I'd put her on the do not see again list.

I saw one advertise Tuesday, Wed she responded to my text that it was that time, then back advertising the next day.  I thought it was pretty quick to be back again.

Some providers will work during that time but others won't.    Some guys request it (believe it or not).
I, myself, prefer to NOT work 1 week every month!!

That is what I gather anyway. "If" that is the case it's my opinion she should have at least offered you the option to reschedule "if" you indicated in any way you were put off by the circumstances. As BB pointed out some gents do like it or at least don't mind & will work around it. A discount to boot would have been an act of professionalism not to mention common courtesy. Again "if" you were not informed ahead of time & "you" chose to proceed with the appt.

...should she let the client know as part of the appointment confirmation process, not details but a simple heads up.."aunt flo is visiting"?   I think she should, imho.  This question assumes she knows beforehand.  The onset during a session can sometimes surprise both and if that is the case, both have got to "go with the flow"  ok, ok bad pun, LOL.  Anyway as another poster pointed out it is nothing to be upset about if the onset comes unexpectedly.  However, I don't think that was the OPs point which I think is should a woman schedule sessions when she knows it is that time?   I do know gents who do like to like to fk during this time (not me), but I can't imagine DATY and since that is always one of my favorite activities, I don't wish to schedule sessions during that time and if I showed up to a session and Red Dollar Days were already on, I would graciously defer...and leave.
As another poster correctly wrote, it IS about communication.

that auntie had arrived, after our meeting had been scheduled but a few days before the day.  I went ahead with the meeting as I wanted to meet her anyway, my hobby schedule is limited and we had discussed what was still on the menu.  A great decision on my part and had an awesome time.  Some time later scheduled again for the full platter.  Its about communication.

use the back door.

That is correct HOF, no 'warning' given, it wasn't until we were in the act that i noticed.  

I agree MNJ, a simple heads up would be much appreciated

I do have a review pending

If you are engaging in sex with women this will happen sometimes.  Most of the time women know their cycle, but biology is not completely predicable.  
It's normal and nothing to get upset about.

Fair point

Women have menstrual cycles. I assure you it's quite natural. They also have hair in their armpits, groin, legs and around the anus. This is also natural. As long as personal hygiene is up to snuff, none of this should matter, in my opinion. But, once again, there is no arguing taste.

That is simple courtesy as many guys prefer not to see someone who is having their period.  Of course, it is a different matter if it arrived unexpectedly mid-act.

Then she probably should of warned you in advance .
I'm mostly a non FS provider but if someone requests the expanded menu options I at least tell them why we can't before the time to give some room for rescheduling. If they go through with it or want more options when they get there & I refuse, then they can't be complaining about it..

Its a common practice by many ladies to use a sponge and hope its not noticed. If I a guy does notice the "obstruction", the woman may simply claim its a backup contraceptive measure. But sometimes the flow is too heavy especially when highly exerted. What really got me pissed off once is when she didn't even warn me prior to DATY. Agencies are notorious for encouraging, even training, the lady to make this a practice.

What are you waitin' for, man? You ain't gettin' any younger!  

Absolutely, sometimes 'life happens' as the saying goes, and you roll with it.  Said provider is a nice girl and by no means was i upset....and i have enjoyed many comments here today, Vallen's may take the cake

.....with an SO at some point in my youth, and being a complete horn dog at the time it didn't slow me down a beat.  But now that I am "mature" and paying for the company of beautiful women, I choose to leave the "red wings" for you younger men (and women)....and thanks for the reminder that I'm not getting any younger, however the age of the women I see is...perfect!  LMAO

After several months in this business, I've noticed a trend: that this period thing is a nuisance and is, in fact, more of an option now a days.  So, I opted out and got an IUD.  I've still had spotting for the past month, but it's so mild and unnoticeable.  If I ever had my period when I had clients scheduled, though, as mine was always sporadic, I'd warn them and allow them to reschedule.

found it to be gross that I was probably exposing my clients to micro bits of blood. Ick.

Scheduled with a well known lady and when I arrived she said Flo was in town.  First time meeting her but had chatted quite a bit and had many mutual friends.  Turned out to be a great TIME TIme time .... another shout out to SD ... My first trip to the Greek Isle's.  Some times we just have to go with the flow.

Been there, as a provider I think we all have.  The professional way to handle it , is be honest let your client know as soon as you do..  ( heads up).....  If he is okay with it.  Fine!    if not reschedule with a discount..  

Just my two cents

oh yes please do .... lol im the most excited during that time and more open to the back door theroy but then again my back door is always open ....