My almost 15yo started shaving about a year ago. He was in 5th grade when he started to get a moustache. He has very dark hair too. It wasn't a thick, full moustache, more like a fair amount of fine hair over his lip that was extra noticable because it was black. It gradually started getting thick enough that I thought he needed to shave when he was in 7th grade, but he was very against it until last year (8th grade). Once they start shaving they have to keep it up.