The first anime I ever watched was One Piece. I think at least! I was four years old at the time, so don't expect me to remember everything! It was surely either One Piece or Pokemon though! I'm going with the former just because I kinda remember Luffy from that time back and the setting was the only thing I remember clearly, it was that G1 base form episodes 2-3, so I guess it can't be Pokemon, but I was watching both by the age of 5, so I don't really know.