Yeah, time.

You need to see what he is like when he has had a bad day. He needs to see what you are like when you have had a bad day. You need to see whether you can trust him not to hurt you and vice versa. You need to figure the limits of the relationship - will you talk about stuff okay? Talk about the hard stuff? Will he be good to talk to when you have had a hard day or will you need external friends who you can do that with etc etc etc?

Only time will tell...