I have had great experiences at all times of the day, even when you least expect it. I've seen travelling providers past 8pm (thinking all the lovely parts would be worn out) and I've had some ATF performances. Also depends on if the guy who pounded away on the girl prior to you was a gent or jerk. In which case, make sure you are the first of the day.

Since I'm a family guy, I tend to hobby during the day and find that most women are fresher at the beginning of the day. However, I think that depends on so many different factors such as number of bookings, whether or not she's a night owl, etc.

How would you really know??...

...unless you ask her, "were you better two hours ago or maybe right after lunch?". I mean she's not gonna say, "ya, know I've just seen 5 guys before you and I'm a lil' tired so lets just get this over with"!  Plus, you may have to do some of the work, too...so what's your best time may be more important.