with my kids it was pretty much from birth due to being able to use guns right out the kitchen door if we wanted to, and did. boys went squirrel hunting when they were 4. daughter about 10. daughter didn't really take to hunting but still enjoys shooting occasionally. boys still shoot and hunt.
as for me, i grew up in PA as well. pellet & BB guns around 6. don't remember a lot of adult supervision. did hunter ed at 12 and thats really the first training i got. rest was just OJT. my old man had 6 boys so hunting was not always norman rockwell-esque. pull up onto the top of a windy, freezing cold mountain at about 530 AM, woolrich, schitty rubber boots 5 sizes too big with 3 pairs of socks. if you survived those mornings, you really liked hunting. most of my brothers bailed by their teens. me and the old man did a lot of mountain hunting.
Great