3 years old: I remember my mom setting up the 1st Mario on NES and I was immediately hooked. Played through a lotttt of the NES library until I was 7, then we got a Genesis, an N64 when I was almost 10, a modded PS1 in Riyadh for x-mas '98, a Dreamcast when I moved back to Ohio summer 2000, a PS2 autumn 2001, an Xbox and GameCube for x-mas 2001, a 360 July 2006, a PS3 x-mas 2008, then I found emulators by 2009 and the rest is history.
Basically, the only console I missed out on growing up was the Saturn and a Neo Geo CD. Which, considering most of the games wouldn't be translated for over 20 years, I'm not complaining.