Well My opinion is that they are never too young to go hunting w/ a parent. I knew when my daughter was 2 that she was into dead stuff... Picture below... This past year Diesel77 and I tooke her on an afternoon Goose hunt. She was fine... A little cold but fine. She is more excited about going out to see deer. I will put a two man ladder stand this year in one of my ok properties so that we can spend some time together in the woods. If something comes buy we may or may not take it.
I think the key is however, don't always say yes to the kid when he/she wants to go hunting.Get Them excited about being out there.Make them curious of whats out there. So when you do get out there, start out with a short hunt. when you are ready to leave, leave even if they say they want to stay tell them it's time to go. Even if they beg.... Progress each hunt a little longer. Botom line, MAKE them Earn it and want it.Your results from this simple drill will let youknow weather they are too young.
Everything in moderation as they devolop their interest.