The age of the child is up to the parent - as the parent will know.......However is some states the regulations state the age the young hunter is legal.
For me I think under 10 is to young more due to physical limitations of being able to handle a firearm safely. Safe Hunting is and should be our number 1 goal!
I bought my daughter a 1100 LT 20 ga. That with the full choke and #4 3" Nitro it threw a good pattern out to 35 yards. I really didn't and would not let any hunter withme shoot farther than that. That is not the point of Turkey hunting I try teach. I teach call Em up close - the closer the better!
Now I did use a mocked-up trigger stick and the ones today are far beter than what I built.
I did have my kids with me and they did experience the heartbreak of not working a bird in close. But to each I simpley said - that is hunting!
JW