The best time to neuter is between 5 and 6 months of age. Always ask your vet to make sure because if you do this too early your puppy can have permissive peeing, but on the other hand if you do this too late your dog will lift his leg and mark on your furniture etc.
Did you know Neutered male puppies makes the best companions.
They are very loyal to their master and very sweet and love-able.
They are just as easily to potty train as the female.