Here is my point of view. As a woman, I would say that sex on the first date is not a good idea if you like this guy. If you know that you like this guy and want to possibly pursue a relationship with him then your best bet is to wait until you know how he feels about you. You don’t necessarily have to wait until you are in a relationship for sex but you should definitely know that he likes you for you and that usually takes more than one date to distinguish.