I've been playing keys since I can remember. My first paying gig was for a local cover band that played country (predominately) when I was 16 years old. Everybody else in the band were in their mid-30s, married with kids, etc. We used to play beer tents and there were always problems with me playing those because of my age. My dad was a professional musician for a long time, before learning piano tuning, and he used to help me haul around a Hammond M3 and Leslie to gigs.
That was a good experience for me because it helped me understand playing to a crowd, tune selection, practicing with a band, etc. Oh yeah, and it also gave me insight into how stupid people are when they are drunk.
So, when did you start playing professionally (ie, earning a buck or two)?