There are no specific rules as far as I'm aware because it's usually down to the individual and their abilities but we can use a rule of thumb. Younglings typically become padawans around fourteen years old if we are to believe the precedent set by the Jedi we know about, for example, while Obi-Wan was still a padawan at twenty five and was promoted to Jedi Knight because he had defeated Darth Maul and couldn't take on a padawan while he was still one himself. The Council bent the rules for Obi-Wan, promoting him without requiring he complete the Jedi Trials, so it's possible if not likely he was young for a Jedi Knight.
We don't really know the full ins and outs with regard to how you become a Jedi Master but we do know of three ways. One is to be given a seat to the Council, which is how Mace Windu and Obi-Wan were promoted to Jedi Master. Another is to successfully train a padawan to knighthood, which is what is apparently the most common way. The third way we know about was to "gain recognition for their service to the Republic".
Ironically enough, if you do indeed become a Jedi Master after successfully training a padawan to knighthood, it's possible the Jedi Council owed Anakin a promotion to Jedi Master the moment Mace Windu offered Ahsoka her knighthood (although, let's be real, he was just covering his butt since he was the most vocal about surrendering Ahsoka to the Republic for execution).
Well now that you mention it, what would be wrong with promoting the Jedi Knights that survived the war and served the Republic faithfully throughout? You don't think surviving a galactic war deserves recognition? It would be like the scene in A New Hope, except with Jedi Knights being honoured for their service with a promotion to Jedi Master. Doesn't sound particularly unreasonable to me.
Or are you going to argue that Pong Krell or Taron Malicos were more Jedi Master material than Anakin Skywalker?
I will point out, however, that Errorname is correct. Anakin did not perform the same work as other Jedi Knights during the war. He was one of the most prolific generals of the war and his peers were Jedi Masters not Jedi Knights. In fact I don't really recall ever seeing that many Jedi Knights during the Clone Wars, but that might simply be because Jedi Masters went on the most dangerous missions during the war and that's the material the show focused on.