What is the average age for a uncirsised to be fully retractible?

I have a 11 year old son and me and my wife don't want to get him circised when should his be fully retractable so he can clean the glans so he wont get infected.He can pull it back like a half or a little over a quarter over his glands but when he does that the skin is tight and squeezes the glands when should his foreskin be fully retractable.