At what age can babies start eating babyfood? Ex:gerber?

I started my son on Beginners oatmeal cereal at 3months and 1week. He was a super hungry baby, and drinks 7oz of milk every 4 hours. Stage 1 is 6 months, so Beginners is for before then. He loved it from day one. Oatmeal is supposed to be easier to digest than Rice and is a good thing to start with. I know the recommendation is 6 months, and I always swore I'd do that with my kids, but he just wasn't satisfied on just milk. He loves his cereal, and I only give it him in the mornings, and he's still drinking the same amount of milk each day.