CP advises cats be neutered at 4 months now. Problem comes with finding a vet confident enough to do it.
I asked my vets if they would neuter/spay at 12-14 weeks so I could get kittens done before they leave me and they said no
A lot of vets won't even do it at 5 months which is mad, I think it was Sunset's owner that said their vets said they wouldn't spay her until she was at least 6 months but as it was in her contract that she had to be done at 5 months old at the latest and the proof of spaying form returned to me then the vets did it at 5 months as they didn't have much choice.
It is a shame that most UK vets don't seem as keen on early neutering as US and Australian vets do.