I really started with my oldest at 5, always showing them the gun and letting them hold it. And really drilling their minds on how dangerous they are. Always doing little "what if" scenarios with them just to make sure they remember. Finally let him shoot when he turned 8. Just practice a lot with them and always remind them what could happen if they play with them (Not to mention, how bad you will beat their asses if you catch them holding it without your permission )