Definitely give them some time! If your son is not used to pets in the house it will take a little while, but I'm sure they'll get used to each other in time and the benefits of growing up with pets are endless. You can show your son how to gently stroke the puppy and explain to him that he is a friendly dog. You can also show him how to feed the dog treats from his flat hand. Just be patient with your boy and the puppy and they'll come right
What kind of puppy did you get?
My daughter is growing up together with our two dogs (very naughty ones at that) and she LOVES them to bits. They love her, too, and unfortunately like to show their affection by licking her face *sigh* but I guess what doesn't kill them makes them stronger. I just make sure the doggies' de-worming and vaccination schedule is up to date at all times.
The first thing Lilly does in the morning is to look for the doggies by shouting "woof woof"

Priceless!