If I recall correctly, around mid-2011, I finally gave into all the hype of the show.
My first exposure came through gaming forums, and like everyone else, I simply mocked it, but in a friendly, non-cruel way. As time went on, much more of the members - friends and moderators included - had gotten into the show (some, however, were in it as a joke and left the fandom after a few weeks, others I'm still unsure about). Because I'm a bandwagoner, I couldn't help but try it out. Though, I was rather afraid of what to expect, so research had to be done.
Know Your Meme was my first site I've seen a full analysis on bronies and the show. It also included a video of the pilot episode. With my parents and others out of the house that one day, I had nothing better to do but watch it. I couldn't quite say I was "hooked", but more or less interested in how things turn out.
After the pilot two parter, I didn't touch upon the show until a week or two later. My curiosity sparked again, and I soon watched The Ticket Master and Party of One - both of which had pretty much denoted my liking of the show. Hence, liking, I wasn't considered a brony, as I personally watched each season 1 episode as the days lazed on, until reaching the Grand Galloping Gala episode.
Little by little, I got infected by the influences of the show. It began with an Applebloom signature, then Derpy-with-glasses avatar, then a few songs added to my iPod, and soon my hype for the Season two opening had grown. I guess at that point I was a full on fan of the show. And look where I am now - most avatars on any site has a pony in it, my iPod has over 250 brony-related music (that's compared to the other 30% of non-pony music in there), and the fact I'm on this site too.
So, yeah.