I think my moment was when I heard stone roses "I wanna be adored" bass intro, just remember thinking that is the coolest sound ever.
It all just clicked and I started listening out for the bass on everything- Pixies "debaser", Breeders "last splash" Nevermind was up there as well, especially that cool little bass type solo on"in bloom" and the bass sound on "Lithium".
that must have been around 93-94, didn't get a bass for a few years after that though (although I used to have a nasty marlin strat copy that I tried to play like a bass)
It was then going to watch bands live when I knew I had found numer one.