When I got my JRT from the pound I only had 2 weeks to get him fixed, so you may have a time line to get this done. The vet also had to send papers back saying that they had neutered Rex. Vet had to do this I couldn't take it back myself, to prevent people from forging the papers. Check your contract if you get a vet to say for health reasons you should wait till 6 months to neuter him you would have to take a letter from the vet in to the place you got him from.