I flew "alone" (without parents) when I was 17. With bus much sooner. Although I have hunted alone since 15 years of old. For example my dad dropped me in the woods at friday and picked me up at sunday. Just later on, actually during this year he revealed that he then wondered whether it was good idea or not. I still think it was a good idea. There wasn't even that many wolves or bears.
I have no answer for your question per se; when you think your kids are ready, I don't know those background.