For me, that would have to be when I attended the Aberdeen Brony Meet last Saturday, and 11 of us went ( forgot to meet one at the train station :c ) It sorta struck me when we group-brohoofed in the middle of a shopping mall and shouted 'For Equestria!' Good times... :3
For me it was a few days ago when i started watching every episode with gummy in it while listening to brony music
There wasn't really a specific moment, I just decided to watch every single episode to ascertain whether I would like the series or not especially after I know of a friend who was really into the show. After season 1 had finished and I moved onto season 2 I found myself really enjoying it and looking forward to season 3.
Two weeks ago. I watched a few episodes, then immediately started trying to draw ponies; I've drawn almost nothing else since.
When I plugged up my iPod to get ready for football practice, and I suddenly found myself listening to Loyalty. "After further review, the offensive line needs to become 20% cooler."
My "oh man I'm really a brony now" moment? Probably when I clicked "next" after I watched the first episode. :derpe: