when he's 2 lbs.  males can be done at 2lbs, females at 2.5 lbs, at least
that's how our shelter does it.

Any time in the next three months that your vet will do him. I wouldn't wait
any longer than that. Your cat should be sexually mature by 7 mo. if not
sooner.

W

As soon as your vet will do it and your kitten is strong and healthy enough.

Some vets have a size minimum (2-3 pounds), some an age minimum (variable, 8
weeks to 6 months). Seems very dependent on the area you live in, the age of
the vet (older vets still seem to follow the 4-6 month advice), and the skill
of the person who anesthetizes the animals (smaller animals take more
skill/precise dosage).

As a person who has seen kittens neutered from 8 weeks to 6 months, I must
say that the 8 week olds seem to take it much better and recover much faster
than the older ones. IME, of course. YMMV.

Any day or week now. He's old enough.

Cathy