Honestly it all depends on whether or not your looking for a long lasting relationship or just a one night stand. If your looking for a one night stand then I say go for it but if your looking for a committed relationship then there is never an exact moment and there is no exact time frame. Before you have intercourse with a person you should decided whether or not you truely care about him/her. Most men I know who have had sex with a woman early in a relationship only tend to turn to them for sex, they are no longer people but they are just objects for pleasure. And women I know who have had sex with men early in a relationship tend to look at themselves and whores and sluts, and then they can no longer think about anything positive about themselves, they become depressed and then they only start to see themselves as good for sex. So all I can say to you is wait until you truly love the person and wait until you feel that your ready.