I'm going to come right out and say that I don't think there's anything wrong with sleeping with a man right away. I've usually avoided it because of the mixed messages given to women in our culture, but the times when I haven't because of the amazing chemistry between us have been the highlights of my entire life. I do not exaggerate! I slept with TheBF really early on, as soon as I could! And this has been an amazing relationship. We're married with a child now. My first love? Same story. And we were head over heels in love for the next five years. Maybe those things would have still happened if I'd been prudish, there's no way to tell, but I think I had those amazing relationships because we had incredible chemistry and I allowed myself to get swept up in the excitement and emotion and I lived in the moment, and those men weren't the kind of hypocrites who would reject me for falling for them.
The double standard about this has been a lifelong pet peeve of mine and I have strong opinions about it. The worst of the bunch are the ones who act like they're super into a woman so she just decides to go for it, and he shames her AFTER he fucks her by telling her that she ruined it all by having sex with him. What hypocrisy! It's a horrible thing to do to someone, tell them that what they did, you know, show him how into him she is, that was wrong and she's going to be punished and shunned for it. That's blatantly deceptive, sexist, and just plain mean-spirited. I think men who do that must secretly be self-hating. Either that or they hate women. Maybe both.
If a man doesn't believe a woman should have sex with a man on the first date, then he should never be having sex on a first date! Ever! It's that simple. The same rules for yourself that you would apply to someone else, regardless of gender. Pretending that you like someone until they have sex with you? Not acceptable. Not at all.