Late 2005. Senior year of college, and one of my roommates and our pseudo-roommate had convinced my other roommate to start watching it, so it was ON all the time in both my bedroom and the suite living room, and they kept talking about it nonstop. Somewhere around the end of the fall semester, I gave in and started watching Season 1 just so I'd know what the hell was going on. I then watched Seasons 2-7 and all of AtS in the spring 2006 semester.

ETA: I forgot a question for you! Hmmm... favorite animal?