Many of the ladies are there on business and have very little time to book appointments after their obligations.  If you are thinking about it, I would reach out much further than usual in advance.

It depends a lot on her schedule and how much free time she has and how much she needs cash and many other factors.

I remember one convention I went to I saw someone I liked, knew she was available, arranged a meeting on the floor of the convention (with the help of a mutual friend) and met up with her in a hotel room that night.

On the other hand, as it turned out, it wasn't the best experience I've had with a PS... she had been at the show all day, she wasn't able to get a lunch break or a dinner break and by the time she saw me in the hotel room, she was starving.  So, it was pretty much a rush job to finish me off so she could go get something to eat.

Next time I do something like that, dinner will be part of the payment.

It's probably best, if you're thinking of seeing someone at a convention, to either plan around a meal, or schedule the appointment enough in advance that she can schedule her time...

Personally speaking (as well as for some of my close friends) I don't schedule anything for the actual days of a convention. It's a lot of work to be on your feet all day in heels, talking, smiling and being happy non stop.  Not to mention the parties afterwards. I couldn't imagine taking any more on that that. What I do is, extend my stays in the city where the convention is either before or after to play with fans