J.K.
Both of my sons were 12 outward signs puberty were emerging in various ways. The first thing I remember was the stink. lol
As for facial hair, it hasn't progressed much past fuzz for my 15-year-old.
Their voices changed at 13. There wasn't much warning, they didn't have the intermittent 'cracking' that many boys do. One day I heard a strange man talking in in the living room and wondered who had come to visit. It was my baby! The same thing happened with his brother. From child voice to man voice without warning.