I don't think it ever really 'Began' until I got my own machine (
BK2K) in 2001. But I do have very fond memories of both Black Knight and Gorgar in the back of the Olympia in Minehead "back in the day". I don't feel old, but that kind of makes me think I should!
Only other time I really came across pins in the wild was a bar that was in a cellar in Bath, can't remember it's name but it was probably something obvious like 'The Cellar Bar' (in fact, think it may have been, but I could barely remember my own name at that time!). Would have been sometime around 1993 or 1994 maybe? Pin in question was a ST:TNG. Remember spending quite a lot of time in there just because it was the cool place to be and really remember the fact that the pin had those cannon type things was a real draw. Spent loads of money on it.
Then, back to 2000 or so, things got a little mental as I did something like five import runs over to Holland and Belgium in Luton vans. Mostly for video games, admittedly (the first was a massive group run for UKVAC), but at one point we visited a guy who had a basement full of probably about 50 pins in Belgium. Me and a mate cherry picked a few all at pretty low prices. Went for DE SW, Fish Tales, GnR and Shadow (to sell on and cover the costs). All about €200 - €300. Also brought back a yellow Pacman upright. Looking back on it, I probably could have picked some real winners if I'd had a bit more knowledge. I remember playing Popeye, F-14, one of the Pinbots and a White Water.
If my crystal ball had been a little less murky, I'd have bought the lot and stored them
Still have the SW though - and it has a tonne of history now as I used to be part of a team that put on a big Star Wars convention down in Devon every year.