Welcome to the forum!
I too have young kids....in fact my daughter is 8 also. She goes with me too, but its merely training and having fun. My son is 10 (will be 11 this week)....he has actually killed deer the past 2 years already with a gun, but has been going with me since he was 5. He is fairly mature as a hunter for his age....much more than my daughter is at this point.
I think its really up to the maturity and skills of the individual. I have not let my son bowhunt yet...thatwill come next year. I feel he's ready now....and if his shooting proficiency is next year, I'll allow him to go. Another thing to check into...some states have laws as to minimum poundage allowed.
Good luck, have fun and hunt safe....