When I was getting close to ten I started doing two lessons a week. A friend of my families also had a horse I would ride for maybe two hours a week.
When I was close to 11 I started doing three lessons a week sometimes, and then for my eleventh birthday my parent's bought me a horse.
In the lessons we had one hour of riding and then half an hour of theory, so we would learn to tack up, feed, horse anatomy, lunging, just general things. Each week we would ride a different horse, although on about half the weeks we could choose who to ride, and I'd always ride the same horse. I'd also ridden my friend's horse.
I read A LOT as a kid so I understood a fair bit of the theory, but we weren't really ready or experienced. I was eleven and no one in my family had ever owned a horse. We were agisted at a paddock with a lot of knowledgable and nosy people and they taught me and my mum a lot about horse care. Not everything was right, and a lot of their advice conflicted but after a few years there I knew a whole lot more.
I kept going to one lesson per week on my own horse as well as Pony Club once a month. Later on I got private instructors who were more advanced and usually had one lesson a week, or one every two weeks. Since my first pony I have leased and owned different horses.
I probably wasn't ready for a horse, but we got by and it all turned out okay. I kind of think maybe that was better than knowing everything and then buying, because this way I could learn about the horse world from the ground and see what worked and what didn't.