The girl I'm dating right now gave up the ass on the third date and she's a solid 8. Most women that I've dated over the years gave it up on the first or second date. Even the really hot ones give it up quickly if you have some game. I usually don't push the issue on the first date unless i can tell they are down, i can usually tell if a girl is wanting cock within an hour of meeting her.
Shit i dated this Russian chick that let me balls deep in her ass and she was gagging on my cock the second night we went out. The first date she gave me a gentle blow job and the second date it was no holding back, straight up freak. The relationship didn't last long, but it was a lot of fun.
I think 2-3 dates is plenty if you are over 21 years old, any longer than that and they probably put their pussy on a pedestal which is a terrible thing or they are really full of themselves. Or you have no game.