My father let me sit by myself when I was 13. I shot a 6 pt, field dressed it, and drug it to the truck. He walked up in disbelief. He never had a problem letting me sit myself again. He wouldn't let me hunt by myself, but would let me sit myself.

Children are all different. Sme are very mature at 13 some act like there 2. Only you can decide whether they are ready. Maybe once in awhile is a good start.