My oldest son started shooting my 10/22 at 4 yrs old. I put a bipod on it and he would sit on the ground with the stock under his arm and I would lay on the ground behind him and help support the stock as well as make sure the gun pointed were it should. Now he is 14 and can out shoot me with a rifle or hand gun.
Now we are starting his friends shooting, they are all good kids that simply have parents that don't shoot or own any guns. It's All good clean fun.