There is no way I can imagine getting serious with someone after having sex with them on the first date. First of all, it kills the mystery and the thrill of the chase. Guys like to pursue and feel like they've accomplished something when courting a girl. And everyone likes that uncertainty in the beginning: Will this or will this not work out? Also, sex on the first date gives people the appearance of not respecting themselves. People should have to earn that intimacy and people should also value that intimacy is at least somewhat sacred. You are a prize, but no one out there deserves to be an instant winner! That awkwardness in the morning after a one-night stand is awful. Most of the time, there are regrets. If you can get away with it with no regrets, and still respect each other afterward, then go for it — but don't expect anything of substance to grow out of it.
It's important to define "first date" in this context. First "meeting" is very different from first "date." Sexual actions taken on a first meeting are completely up to the discrepancy of the two parties and are 100 percent influenced by uninhibited emotion, whether or not it is alcohol induced. A first meeting can end in a swap of phone numbers OR it can end at the crack of dawn the next day, clothes scattered about and foggy recollection of the night before. Both are perfectly acceptable outcomes and the two (or more) adults need only be able to cope with the decision they made the night before. A first date, however, is something different. Two people decided to meet and share an experience with each other, having passed the initial vetting of a) attraction and b) "Can I stand to be in a conversation with this person for more than five minutes?" In this case, I'd advise to take it slowly, although part of me would like to shout, "Women's liberation — do what you want and be empowered!"
He Said, She Said: Siblings, Rich and Emily Santos.