I think I took to it when I was a kid because I idolize my dad, and I could tell as a kid that he was FIRED UP to go. There were some times we went when I was super small, but then there were also time I had to stay home until I was "old enough." I think the trips NOT going built the desire more than the ones where I did go. I wanted to run with the big dogs in a terrible way. When I started to get "old enough" he made it clear that if I couldn't hang, I wouldn't be coming back out. Looking back, he set pretty small standards, but they seemed big and important and I was dead set that I hit them. I carried my own (small) pack. I didn't whine (too much) when it was cold(ish). I sat (relatively) still when deer were in the plot. That's what men who got to go hunting did, and by golly that's what I was going to be.
I'd say if the kid has a good relationship with you, he'll probably want to go. Keeping him from being miserable but also pushing him a bit while making sure he knows that only the guys that can hang get the glory of going will probably do more to keep him interested than catering to him or worrying if he gets to shoot something. I hunted a long time before I got to pull a trigger. Probably 4 seasons?