Friends first, now transitioning to an actual relationship!

Okay, so one of my closest guy friends just got out of a long term relationship about a month ago. I've always been there for him and he has always said I was his best friend even while he was in a relationship. Myself I have also been in relationships while knowing him. We both have really cared for one another all these years but have been with other people so its all kind of all been about timing. Since now we're both single, we're hoping to start a relationship with one another. He says he is fine and is ready to move forward, but I am slightly hesitant because it hasn't been that long. He's a pretty straight forward kind of guy, and I believe him when he says that he wants to be with me because he truly loves me. I think I have a small insecurity that I might not measure up to someone who loved him for so long. I tend to compare myself to his previous girlfriends, wondering why we weren't together earlier. I just want to know that I'm different from them in his eyes, and that I will love him differently since we were friends first. Any advice on how to make sure we're both ready before jumping into something new? Also I definitely don't want to ruin the friendship because I truly care for him so much! Anyone else been in a similar situation?