For me it was about 8 and I got it for my 9th birthday (I think, 3rd grade anyway). It was the base model, below even the Red Ryder. Daisy still makes a version of each, you can buy them at WallyWorld, at least in Oklahoma and Texas you can. :)
I'm not sure how long it was before I was allowed to take it out by myself, not long I think, although it probably seemed so at the time. My cousin, who had the more powerful slide action (Which you can also still get) and I used to shoot through soda and beer cans (steel, not the thin aluminum used now.) His would reliably go through both sides, mine usually only one side. No one's eye got put out. Although a ricochet off a tree trunk did get lodged in another, older, cousin's temple, without drawing any blood. He figured no harm, no foul and AFAIK, the adults never knew about that.