If you're planning on getting him circumcised- do it now! My husband was 24 when he had the operation and it was extremely difficult on him physically. It took much longer to heal, and he is still having issues from it.
when he is taking a shower take the foreskin back slowly and wash under there he might cry but its because of tickleness and while under there clean with water at right temperature so later on it will move more freely back and forth
1. Let your son sleep without boxers and be around the house naked a little. It would allow the foreskin to expand a bit.
2. Apply petroleum jelly to the foreskin daily for a couple weeks, gently retracting each day.
3. Have a doctor examine your son's penis and give some extra advice and possibly medication.
4. Circumcision would not be a wise option, it may cause infection especially if under the foreskin is dirty.
My husband is not circ. and when he uses too much soap and hot water his becomes tight. I would try cooler water, very mild soap, and some oil--we used olive oil.