Cool stories here. It's interesting to see how varied experiences are.
I started playing guitar when I was 13. I was playing in metal bands by my late teens/early twenties and got pretty good. Played off-and-on over the years then decided to start getting back into writing stuff a couple of years ago.
I've gotten more serious with my writing and started laying down some woefully inadequate bass tracks, thinking I would just find someone to record them properly for me. In the meantime I kept trying to improve them myself and discovered I was having a great time.
Now I'm practising scales, honing technique, and enjoying things I never enjoyed on guitar. And my bass tracks are improving bit by bit!
So probably I would say I've been seriously playing for one or two months. Just using my wife's bass she never ended up using herself until I can get my own.