Almost all decent agencies will have one or 2 good girls available some time that day. All the brothels and AMPs have girls waiting to be fucked.

You can try certain Indies -- a good sign that they have no business is they are on the boards all the time.

Say you find your schedule suddenly frees up due to a cancelled oblugation work or whatever and you suddenly find yoursel with some time to kill and a desire to hobby, what is the best way to find a day of appointment other than sending out a spate of emails to providers you have not seen before who are probably not available and now dont have time to screen. For eg, are the "available now" postings on Eros actually current and you are likely to get a response because the girl is at her incall waiting for calls?

Backpage, Agencies or Brothels are the easiest way to find a same day appointment

It's possible to see an indie on a same-day basis, but it's not likely.  Most indies require time to screen and check references, even if you have p411 and date-check.

My own personal experiences would say you'll be able to reach an indy for a same day appointment maybe one time out of 20 or 30.  

Your best option is to contact any local indies that you might want to see in the near future.  Tell them that you have a problem scheduling in advance and would like to get pre-screened for a possible future same day appointment, if that's OK with them.  That will increase your chances.  Not by a lot, but somewhat.

Or, just contact one of the many agencies we have in the area.

And that would be your best bet! Start a dialogue with a couple of providers that your interested in and give them your refs in advance so the screening is out of the way... Then when you are ready to meet she is more inclined to take you on the same day....  

Oh and P.S. -  I believe the "Available Now" feature is in 2 hour increments.  A provider must log in every 2 hours in order for it to remain constantly available...