It depends on where you are meeting or taking them before. At a bar,expect them to be drunk, at least somewhat. But from other places, they will be sober the first time with you.
Unless a girl is truly drunk, alcohol is typically just an excuse to delegate responsibility for the hook up. I've hooked up with plenty of women where both parties were sober and in fact I prefer it that way, or with the girl slightly buzzed if it makes her let loose a bit more.