I started my boys on safe gun handling with talking about it often very early on. Every time I had guns out of the safe, if they asked, they got to touch. Once they got big enough to hold them, they had to ask "Is it loaded" followed by "show me". Thus they had to start to see, and understand the manual of arms. Every trip to the range, we go over the 4 Laws of Gun Safety.
At 6, they could shoot the 4 pound 10/22 and at about 7 I added in Ruger Pistols. They got introduced to ARs at about 8 and the older one has shot the 9mm pistol in a few matches and just started on 12 gauge shotguns. He turned 12 on November 1 and shot his first deer with a .308 on November 2. He has about 7K rounds under his tiny belt, his younger brother about 4K. They, with my wife, shot the Ruger Rimfire Worlds in July, which was the first time any of the three of them had ever handled a firearm not under my direct supervision. I got several compliments on their safety from their squadmates. The 12 year old, with rimfire has several 5 shot strings in SC and RRC that are in the 1.9 second range, so he has speed too.
Yes, I am proud of them, but I am VERY safety focused. They are very much boys, but I allow NO goofing around on the range. Also, if they are irresponsible with their schoolwork or behavior, the shooting goes away. The older one has lost the chance to shoot 4 or 5 matches. Last, I never forced them, they always asked. I would always show them each weapon, the ammo and explain the recoil impulse, sometimes with a thumb to the shoulder before they got the chance to shoot, or wait on a particular firearm. If you are honest with your parenting skills and the maturity of your kids, you will know. I have seen a lot of kids forced, or allowed too early and there is damage and safety risk there.