Well my opinion is if you want to teach proper money saving, now is a good time. If you give him more than a few bucks, have him save half of it. I know many banks won't let you start an account with a small amount, but if you start a "piggy bank" he will have enough in it by teenager to start an account.
Banks make exceptions for kids and almost all of them will let you open a savings account for a kid for $5