I'm retired, so I can go anytime of day.  I tend to prefer around 11 or noon, rather be one of her early, or first, appointments of the day.  If you are still working, or have a family, those situations will probably have an effect on when you can go calling.
Same for her, as many providers have real life jobs, or are married with families too.

LLAP,
Swim

It depends on your schedule and how popular the lady is that you want to see.  Some ladies see lots of clients in a single day and to be honest I don't want to be the 4th guy that she has seen that day......in that case I would book really early in the day so I could hopefully be first.  If its a lady that is more selective than you can see her when it works for you.  If you want to share a bottle of wine or have dinner then that is clearly an evening date.......bottom line it just depends on the lady and location.  The more expensive ladies probably see less clients and the cheaper ones probably see more.

I hope that helps