I started mainly by taking care of my sister (well, watching her after school while waiting the couple of hours for mom/dad to come home) when I was about 10 1/2. By 11 I was also watching kids of friends-of-the-family, who lived in the apartment block next to us, and whose mother worked with my mom. That gradually progressed to me being asked to babysit for them evenings for a few hours - often something like 5-9 or so, while the parents went out to dinner or a movie. I also babysat upstairs (some of the best, well behaved kids EVER - 5 year old boy would say OK and run to the bed when you said bed-time!).
Within the same year, I started getting calls from other people, who were friends of people I was babysitting for, wanting to hire someone for an evening. I had never met them, but I started babysitting for a few other families that way. It was fairly easy, since at the time I lived in a military PMQ, and so I was always only a building over from my parents if anything went wrong (nothing ever did), and I knew half the people in the area, as well as who were MPs.
I just remembered I was even unofficially hired to watch a CLASSMATE, who was a rather immature boy. We were friends anyways, and just hung out for the evening, but his mom gave my mom 10DM to give to me later
So, no, I don’t think thats too young, but in my case, starting off with a sibling, and close family friends was probably a little like a mother’s helper situation. Give your kid a chance to watch a child, while you’re nearby (at the neighbours or something), but for a couple of hours, and see how she does. If she has problems, she can easily get you, but on the other hand, she’s the one in charge.
As for being “latchkey” for us, we actually had a bit of a choice of walking to my mom’s school and go home with her, or take the bus and be home for an hour or so (or more if she got caught up in something) on our own. It was good to have that responsibility, but also the knowledge that we could go see her instead. My mom also always called at a certain time to be sure we were there - basically when we’d be home but before we were likely to go to the park in front to play. Good safety thing there, too.
Ok, I’m blabbering, but I’m having all these cool memories of the base, and I want to share!