How do you know when it's the right time?

I have a friend. We're both in our freahman year in college. We both really liked these guys and we all have been hanging and just talking for a few weeks. My friend ended up having sex with the guy she liked and he completely changed after. He became a real ass to her and the guy i like says he's not like his friends and wouldn't do that to me but i just dont know. I really like him and very interested in him but I'm afraid he'll do the same thing to me