Yeah. Everyone fucks really fast now. I hate it, so it is possible to find bfs who don't mind. But it's not easy either! He has to really want you. And hell he could still be fucking another girl anyway, until you're exclusive.
In other words, it's best to wait at least a little bit, at least until you're comfortable with one another and have a better picture of what each of you want in the relationship. But when it comes to how long you wait, that depends.