My daughterwill turn 8 in about three weeksand has been shooting a bow for almost 4 years now, she started with one of those plastic long bows....I have really been thinking about that very question and I have come to the conclusion that she will need to pull around 40#'s and be very proficient with it before I will let her hunt with it...I guess ultimately when I feel she is mature enough and has proven herself to make responsible decisions, as well as be proficient with her bow. I think for each kid it will depend on how they develop and how much time you spend "showing them the way"...I am waiting on that day like you can't believe....
When she was 5 she asked me if she could go hunting with me, so I pulled out the rifle (knocked the dust off of it) and took her hunting. We saw a few deer and she was hooked, then after a couple years of her practicing with a rifle, she shot a long horn spike last year with a litlle help from dad.....We have continued to practice since that time and I feel comfortable that this year she will do well without dad's help on the riflethis year (don't get me wrong, I will be right there with her but she will be pulling the trigger)....It is great to get the kids involved and to spend time with them in the outdoors.....