And if you're feeling immensely cool
having just had a new born child, you could keep a journal
for him for a couple of years, or more. Your child wouldn't be able to keep a journal until a certain age, so you could do it for him until he/she was 13 or something.
And once you had given them the journal, you could read it whenever you like, because you wrote it. It could be about you and your child simultaneously. Imagine how awesome it would be if your father turned to you this christmas
and said "for christmas this year, I'm going to give you about 15 notebooks that say what you did everyday of your life until you were 12 years old."
If you're going to keep a journal, why be selfish? Give that time to someone you kind of like. Besides, your kid isn't going to be doing too much without you for the first 10 years, so what you write for him or her is probably going to be what you did too.
Think of all those random childhood memories you have, but they're too vague to recall. Think how much would come flooding back to you.....