In all honesty, I can't remember when I started to use the computer. It was just always there. Granted, back then I only used it for computer games. None of this internet and homework nonsense.
Got my first computer in 1998-1999, that's when I started using computers. I still have that computer in my basement and it's still working perfectly. I use it to mainly play games such as Roller Coaster Tycoon and Zoo Tycoon, no internet.
Since I was 5 or 6 I played some learning games on the computer at my mom's office. Then when I was 10 or so we got a computer at our house and I got exposed to the internet on a nearly daily basis.
I started using computers when I was around 4 years old to play some entairtaining games to learn things. (Things like the letters, being able to write and talk correctly...) until I started using the internet and that I was a little more fluent with those stuffs at age 12. So it's been currently 16 years that I touched my first computer and 9 years of internet usage!