what angel146 said...plus...wear a condom. We don't want to see you here again in two months saying 'I'm late'.
If you two feel you're ready, then go for it. Sounds like you both understand where the other one is at about how you feel about each other. If that's ok for you, then who are we to say whether it's ok or not?
Wear a condom. If he's...over excited, get him to wear two
It isn't a make it or break it (sorry bout the pun) deal. If it happens, it happens. Don't put stress on it or you'll tighten up with nerves and he'll be as limp as a noodle. Just do whatever makes you feel comfortable together.
Oh, and you really should be on top to control him. It'll let you control it and will hopefully relax you so you're not bracing for the thrust.
Wear a condom.
Communicate.
Enjoy