I started my grandson with a Crickett .22 bolt action rifle. He was 5 when I first took him out. He is eight now and a very good shooter. I have a 10/22 for him but the Crickett still fits him better and he prefers using it over the 10/22 because he hits what he's aiming at.
One thing about paintball........you are allowed to shoot people. Some habits can lead to problems.....
A lot depends on the child. My granddaughter turns 6 next month, but she isn't ready to go shooting yet. But, grandpa is prepared with a pink Crickett and a pink 10/22!
Kudos to you for doing the right thing!
Check out post 62 in this thread: