I started my daughter at 12. That being said my dad gave me and my brother .22's a box of ammo at 11, and 10 to shoot. With out adult supervision. That being said after years of carrying sticks, pointing and going bang.
I brought my 11yr old there last October when he was 11. He was shooting my Winchester pump 22lr. I bought my son a Ruger 1255 Boyscout 10/22 for last Xmas for his first gun.
I should add my own kids to this.. My almost 11 year old son has been going to the range for a couple years.. He shoots his .22 bolt action mostly, and he shot his first steel challenge last year.. My 19 year old daughter has never been, and I will never personally take her. My 4 1/2 year old is very familiar with the range, and comes often, but never shoots.
My daughters started shooting .22 rifle and handgun at 8 and 10. Last year I picked up a Chipmunk that my 7yo granddaughter started shooting this past weekend.
I think my boys were seven, mostly .22 rifle and then eventually .22 pistol. My oldest at 15 shoots my AR, and has popped off a few rounds in my 1911 .45.
I first went a shooting at 8, received a 20g shotgun for my 12th birthday, killed my first squirrel that year.
My son has been going since he was 9, a lot of .22, has fired .38's & .357mag. My 10 & 8 yo daughters have fired pellet rifles, but both are itching to go this year.
My 5.5yo son was playing with his Clone Wars NERF blaster today and explained to me how it works internally and was asking about why different NERF blasters have different sights. for the most part he was correct and when I corrected a couple of minor points and explained the sights he said "you sure know a lot about guns dad", then asked when he was going to get to shoot real guns. I told him when I thought he was ready I'd show him how to shoot a BB gun and we'd work up from there. I'll probably start him on AirSoft but we'll see.....I can't wait, but I will; until I have full confidence in his ability to be safe.
<enter way back machine>
when I was 8 my dad saw me shooting a suction cup pistol at some action figures and corrected my stance and grip, then explained proper breathing and trigger technique (on a suction cup gun!). after about 20mins of that lesson he grabbed his keys and off we went to get a BB gun, a crossman .177 pump rifle model. I shot that on the makeshift range spanning two rooms of our apartment in Somerville for a few months and then graduated to using his Ruger Security Six revolver with .38 ammo (edit: at the real range of course). by the time I had just turned 11 he was tired of paying for the wad cutters so there was a brand new Ruger MkII .22lr pistol wrapped and under the tree for me that xmas; mom was not pleased. I still have the MkII, was just shooting it at the pistol pits a few weeks ago after putting the .40 away and it'll be the first real pistol my son shoots...and my daughter after that.
One of my first memories was shooting at Riverside with my dad at about 5 (he of course was helping he hold the rifle). Got my first BB gun around 7, and bought my first real rifle with paper route proceeds at 13. It was an Interarms Mark X 30-06 with a Manlicher stock (still have it of course)
My dad let me shoot a few times when I was about 5 or 6. He was holding the rifle, I got to aim and pull the trigger. I don't know how but one of the targets survived for a few years after. I think my mom 'lost' it in the move. I didn't shoot till after college when my friend took me to her range and sparked me to get my ltc. But at 5 my dad thought I was ready where at 16/17 my brother thought he was ready and being the know it all that a 16yo male can be ended up having the recoil hit him in the head.
My 8 year old is ready, and I will take him to shoot the P22 as soon as I become a club member. As a father you will know when the day comes.
He has nerf guns which we use to go over the firearms' basic safety principles. The latest he got is a two barrel shotgun where you put the "darts" inside shells. After you shoot it, you open it and the shells are ejected. Works just like a real shotgun. Perfect for firearms training!