As a short notice man, I would definitely recommend that you pre-screen with some ladies that you admire via PM or email, and let them know that you aren't always certain of your availability. Ask them what's the best time of day to get a short notice appointment.
Depending on a lady's incall situation, she may need to get a room first, or if she has a permanent incall, there's probably a period of time of the day that she's there waiting for calls. Depending on your timing, having a roster of ladies available at different times would probably increase your chances of a positive meeting.
You'll get one of two reactions:
a) either they'll think you're a timewaster, since you're not booking immediately, or
b) they'll appreciate the fact that you screened with them early since you expect to meet them quickly with little to no time to screen them before your meeting.
B would be my choice as a provider. I'd be more willing to meet a man who showed a little concern for my safety than a new guy trying to rush me into an encounter.