Mine was a LONG time ago (must have been '81 or '82) - I was in KB toys and they had a G1 Megatron. It wasn't even the transformer brand one, it was a couple years before they came out. It was from whatever line spawned him - Microman I guess? I remember thinking it was fantastically complex. I was so bold as to take it out of the box and fiddle with it (I was just a kid and did that a lot - I'm surprised no one ever busted me for it). I didn't get to buy it. So really, the first TF I saw wasn't even a TF, but I knew it was something special. Technically the first actual TF I saw was Bluestreak, a buddy got one for his birthday.