My schoolmate Darren and me started getting into Maiden, UFO and the Scorpions when we were about 12, listening to records round his house most nights. His other brother had gone to uni leaving behind a Kay bass, which got my attention tho i couldn't play it.
Around the same time my older brother said he wanted to learn guitar, inspired by a bunch of his friends who had a school band.
I didn't want to be outdone, so got a bass - a godawful short scale Satellite - and a practice amp, which i paid off doing a paper round while dreaming of being Steve Harris. That was 33 years ago. (I still want to be Steve Harris a bit tho...)