What Bruce said. Get a feel for the child. Take them with you when you feel they are ready (able to set still for long periods). When they start understanding and have seen you do it few times, then you can probably make the call. I dont know from experience yet, my kids are 5 and 6. I wouldnt dare take either of them out yet. I do take them out with me to scout. They can find tracks, rubs, and scrapes already. My youngest can even follow a trail pretty well. I dont think they have the patience yet to set in a blind and hunt with me. I feel right now it would be more detramental to force them to set bord for long periods of time, waiting.

Lifes a garden, dig it.