Good vet
I would absolutely wait until at least 6 months to neuter. I had Ranger neutered at 6 1/2 months, and he DOES NOT mark, in or outside. I got Ryder at 14 months old, and had him neutered soon after. He does not mark inside either.
He will most likely need a few teeth pulled so it is a really good idea to wait and do it all at once
