At 7-8 years old while playing on deluxe paint on amiga. Then I though that it would be wiser to chose a "standard" job, but I've end up as 3d artist in pre-render production so I just made a step into video game O.o.
When I was 7, I got Secret of Mana on SNES, and I would copy the pictures of the characters from the instruction manual. I remember sitting in school, trying to draw all the weapons in the game from memory. My first job I ever dreamed of having was to be a concept artist for Squaresoft.