Keeping in mind that the ladies are busy how much time do you allow someone to get back to you before you move on (assuming that you are not pressed time wise)

If something is set up in advance I can be there at anytime that works best for you. If it is last minute I generally need only less than 45 minutes to be to your door

assuming that the guy called to cancel, I wouldnt move on. If he happens to be a no call, no show; I give 30 mins time before I move on

while some providers are on top of the ball and will get back to you much sooner, shit happens and sometimes it takes a while to get a response.

Providing all the info that a provider requires up front will help.  Including data like what date/time/length you're looking for should elicit a response.  Asking for rate info when it's clearly on their website or asking for discounts below listed rates requires balls and be prepared to be ignored.

If you're not getting a response, give up and move on.  If you're trying for a second or third time, maybe you're being dropped on purpose.  There are way too many well reviewed providers in the TER database to be hung up on a particular provider.  Being stalker-ish and making too many inquiries is an easy way of getting on a provider's bad side and get blown off.  Forever.

Bob