You don't have to wait for exactly a year (nothing is set in stone here)
But the fact is, as a dog approaches 3 ... he is going to be hitting his prime.
So if you want to match a dog while he's in his prime, then you're going to have to wait till he's about 3.
Now, as far as how long the actual schooling takes, it depends on what you consider "schooled."
If you want to roll the dog once or twice, then match him, you're not schooling your dog at all ... you're just seeing if he'll fight, seeing if he has ability, and then betting on him.
If you're actually schooling the dog, this means you're going to roll him 4-5x against different-styled opponents.
You're not just dropping him in there with dogs "a couple times," then betting on him.
You're selecting opponents based on their styles, to expose the dog to different styles. This takes some time.
In truth, I think MOST dogmen don't actually school their dogs at all. They roll them a couple times "against whatever," then match them.
If you actually school the dog, it's going to mean against at least 4-5 specifically-selected opponents. And, if you give the dog 4-6 weeks to heal in between sessions, then you're talking about a 4-10 month process ... which also allows the dog to mature from between when he's first started, to develop through the schooling process, to finally be matched for real when he's in his prime.
Remember, I am talking about BEST practice, not "standard" practice
Standard practice is, bump the dog, roll him again, then shoot (match or game-check) the dog. Next!
Most people do not engage in best practice, but that doesn't mean what they do is correct or in the best interest of the dog.
I know people who will match a dog right after his first roll, if he looks good.
Sure this can be done, but the dog can hardly be called "schooled."
Most dogs (with intelligence) get progressively better, after each session, set 4-5x down, in 10-15 min sessions.
It's like sparring for 3 rounds in boxing. It's long enough to teach the dog, but not long enough to take anything out of the dog.
Jack