How do you know when right time is to say yes ?

I liked this guy for a few months now and he goes to my school but we havent really talked that much but he just started talking to me on facebook and he asked me who I like and I didn't wanna tell him so I said if u tell me then I'll tell you and he said he likes me and then I told him I like him too. but then I stopped liking him for like a day, I guess I just thought it was awkward but then I started to like him again, and now I can't stop thinkin about him. he told me he was gonna ask me out but he was scared I'd reject him and now I feel like when we go back to school, he'll ask me but I don't wanna just rush into a relationship cause all of my past ones were like that. so how do I know when the right time is to say yes and be in a relationship, cause I really don't want to be hurt.