Been receding since a 14.
Aged 17, then gf kissed back of my head (don't!) as I was sat down. "Ah, I just kissed your bald spot"......"My WHAT?"
Now 35, about 2 months ago, triggered by sick of paying for a hair cut and being shown the back of my head, I went out and bought clippers.
Grade 3, won't even look back now. Should have done it at 17.
EDIT: Mine also looked reasonable from the front, but from the top and back it was a different story.
Further Edit: also convinced bald spot cause by later-found-out-child-molester teacher, that used to lift me up by my hair in primary school. Shit.