what age to neuter

a male kitten. He was born March 31.

some vets will do it earlier, but mine won't do a male until he is 6 months old.

Yep, I agree. 6 months for both males and females. That way, they're old enough to get through the surgery but still too young to make kittens.

The vets here will spay/neuter, when kittens weigh 2+pounds. Rowdy was spayed at 10 weeks and was trashing the house, the same afternoon.

Before Rowdy, I always altered, at 6 months. The Humane Society won't let pets go home, until they are fixed though.

Over here, the advice is to neuture a male when he is nine months old.
The general idea is, that if you neuture them when they are younger they are at greater risk to develop urinary problems later in life.
But it also depends on the circumstances, like whether he's an indoor or outdoor cat.

6 months is also a good time, since they haven't started spraying yet. That is one thing you want to avoid!!!!!

LOL
yeah, that is one of the "circumstances" I had in mind

Aggressive behavior is another.
My youngest male is 7 months old and has not yet been neutured.
I plan to allow him his full 9 months, also because he is still quit small.
A few days ago he suddenly grabbed my hand and started biting it.
When I said : He, what ARE you doing? he immediately stopped biting and started licking my hand instead.
If he hadn't I probably would have taken him to the vet the next day.
Chop-chop for you my friend

I like to get the males done around six monthes but I plan to get the females done around 4 monthes.