When do you give up and move on to another provider ? I've been in contact with a lady over the last two weeks in regards to our appointment that is scheduled for today. She hasn't responded since yesterday. At what point should I just say F it and move to plan b? I usually only do two emails max a first one to establish contact, then a follow-up. If she doesn't respond I'd move on to the next girl. But she's initiated the conversation and now just silence.

..last week in an initial email I requested an appt, included a blurb about myself as well as references. Never heard from her. I moved on.

I would send one more communique this morning reminding her of your scheduled rendezvous.  By this point, you should have initiated contact by phone or at least text, and you should use that as your main vector in contacting her this close.   I wouldn't move on just quite yet...give her a chance that she's not flaking, especially if she has a quality reputation.

If you've schedule an appointment with this person and you haven't received a confirmation within 24hrs of said appointment, I think it's safe to move on, but be sure to read her etiquette and terms.