Revolution on Cats. How long before fur regrowth?

We have a mothercat and her 5 kittens, now 6 months old (the mother was a stray). Due to mange mites, mothercat and one of the kittens is being treated with injections. For them and the rest of the kittens, they are all also getting Revolution (primarily because of mites although they have a few fleas too). Since these are indoor cats, after two more months, I should be able to discontinue use. Two of the kittens show a fair amount of hair loss in the area where I applied this stuff last month. I applied it a little lower this time around, but wondered how long it takes for fur regrowth? My vet has never used this product on cats before (it was recommended by a veterinary specialist).
Frontline doesn’t work on mites. That’s why we are using Revolution. Otherwise, I’d use Advantage or Frontline.

My cat had to have his head shaved, and it took about 2-3 months for it to fully grow back.