My first Episode was the very first episode,like a few other people.
And the reason I became a brony, my Girlfriend and the fact that the show just kept nagging at my brain. But at no point did I ever dislike the show or think it was for girls. (And in fact, when I was younger and before the show was around, I used to play with a My Little Pony toy with my sisters.. So that may have helped too.)