You need to follow the laws for your state. My boys had their rabies vaccine right before they were neutered at 6 months old. At the same time the vet will also check his teeth to look for any retained puppy teeth. Yorkies have a tendency to retain teeth and while they are under for their neuter is a perfect time to have this done so he won't need to be put under twice.
__________________ “Never argue with a fool, onlookers may not be able to tell the difference.”  Mark Twain |