When you first contact a provider.
How long should you wait for a provider to get back to you?
72 hrs is my thought. But I've heard I'm wrong.

Many providers are flooded with emails and phone messages.  Some will respond but many do not.  

If a lady does not respond in a day or two, move on.  Either she is a poor businesswoman or there was something about your message that caused her concern about you.

I'd e-mail her twice.  If no response, then move on. Same with phone calls.

There is a delicate line between being persistant and becoming a stalker!

72 hours is way way way to long, you should at least try back by the end of the day.

I agree, usually if a provider responds she is worthwhile. The ones that don't respond are the flaky type and if you pursue them you will question yourself why you did. The more responsible, the better the service. Not always, but most often.Just my two cents. BJN