If Junior is interested, there's no such thing as "too young" to go shooting with Dad.
I was about 4 when I started with a Daisy BB gun; I don't remember the model, but it was styled like a pump shotgun, held 50 rounds in a magazine tube that was loaded at the muzzle, and cocking it was accomplished by pumping the front slide; a toggle that looked vaguely like an inverted Luger toggle folded downward during cocking.
When I first got "my" BB gun, I was too little to reach the trigger if I held the stock against my shoulder, so I had to tuck it under my armpit and bend my head down to see the sights. And of course my little arms weren't strong enough to cock the gun at first.
It worked that way, and I had a LOT of fun shooting it with Dad. I grew into it pretty darn quick, too.
(I absolutely WOULD get the kid eye protection - I was lucky back then, but I wouldn't count on luck to preserve eyesight if I were teaching a youngster to shoot today.)
Oldgringo wrote: . . . the boys wouldn't mind either their Dad or us and flagrantly waved the gun in all directions and fought over it, etc., etc.
Dad was pretty lenient in a lot of ways - he didn't micromanage me - but there was a line you just didn't cross with him. He absolutely WOULD NOT have tolerated this behavior in me - the loss of the BB gun would have been the least of the unpleasant consequences that followed.