Hello my daughters have grown up around guns all there life. There has always been a gun on me or in close proximity in the house . With that said I started shooting with them at the age of 3, with them sitting on my lap and letting them sight the gun to target and pull trigger with help along the way. I used a low power airgun with the stock cut down, a red dot sight (easier to explain sight picture, "put the red dot on the balloon") and reactive targets such as balloons or cans of club soda shaken up. I believe it is never to early to start them, safety is a must, one of the most important lessons you can teach them is a safe direction ( an area the gun can be pointed when operating and holding the gun (from taking it out of case/safe, engaging safety, powering up optics, loading/unloading etc) where if the gun was to discharge that it would cause no harm to personal and minimal property damage) Granted most of this will be done down range but our gun has to get from its resting place to the range. Example I take the gun out of the safe to place it in it's case to go to the range: 1 identify safe direction, 2 remove gun from safe, 3 point gun in safe direction, 4 ensure gun is safe clear and empty, 5 place gun in case, 6 transport gun to shooting area still being aware of muzzle even in the case. Unfortunately accidents will alway happen (that why we have car/ home insurance and loading/unloading ports) BUT if we are muzzle aware and use a safe direction you will minimize a negative outcome. As for what gun to use I would look at a crosman 2240xl with a red dot sight a 7 inch moderator/ suppressor(you do not want to short of a barrel as so you do not sweep you/sons hand when using it as a carbine) and a cut down shoulder stock. This will make a nice light carbine with a good trigger and can be used indoors or out depending on your range set up. Well good luck getting your son behind a gun, start early and often any you will have a shooting buddy for life, my daughters still shoot with me even a 19 and 24 hope this helps Eric.