Wow, I can still remember when mine were that small (has been a while back)...but I can tell you this, You are embarking on the most difficult but without a doubt the most rewarding thing you will ever do.
Talk to them, read to them, show them what you know and lead by example always. They remember and retain more than you can imagine.
Any guy can be a father, it takes a lot more to be a "Dad"
I could go on for pages but I'll just say congrats and tell you to relish every moment...even when he gets on your nerves. Mine sure did that plenty, but he's still "my boy"...always.