Well, if you won't count series I watched not knowing they were anime (Yatterman, Yattodetaman, Paul no Miracle Daisakusen, General Daimos, Tiger Mask, Captain Tsubasa, Sailor Moon, Arrow Emblem: Hawk of the Grand Prix, Mahou Tsukai Sally, Mahou no Mako-chan and other old stuff when I was 3+ and Dragon Ball, Slayers, Saint Seiya, Pokemon and few others when I was 9+), then it would be in middleschool when I was 13 or 14 years old (now I'm 21). I don't remember exactly when because I have terrible memory for dates but sometime then my friend gave me Hellsing and after that I wanted more. He gave me Evangelion, Trigun, Fullmetal Alchemist and Elfen Lied and after that I started downloading anime on my own (though I don't remmber what title came first). I didn't watch much (MAL says 181 copleted titles) because I love games too and I'm usually spending much more time on them but I'm very happy I started watching anime.