How do you know when you're ready to move in with a boyfriend?

Okay, me and my boyfriend have been together on and off for 5 years now. We're both 23, I'm still living at home right now, he's living with his parents for a few more months, and he's lived on his own for the past few years by the way. He want's me to move to a city about 30 minutes away from here, but I'm not ready to move out yet. I thought I wasn't ready, but a friend brought to my attention that maybe I'm just scared to move out. Which is true. When he was living on his own I was over there almost everyday, and I see how it would be to live with him. It would work out. We've talked about moving in together in the future, and talked about similar things that we want to do in the future. But I didn't know he wanted to live together this soon. But I'm not sure if I should take the risk in a few months, or wait till I'm ready. But then again what if I never feel that I'm ready, should I just move out anyway? Cause he's kinda mad that I don't wanna move in with him yet, I don't know what to do...Any suggestions, opinions? Thanks for any responses!