If you want, neuter him around 6 months. That's better than not neutering if you are unable to guarantee that he will never be around an in heat female. Which means that he must never be off leash or left in the care of a relative, or left unattended in a yard that he or another dog can dig under or jump over. Intact dogs will go to great lentgths to get to an in heat female. Even a dog that is normally ok about staying with you in a yard, unleashed will be likely to run off if they smell an in heat female. Or a dog that normally won't jump or climb fencing, or dig under, will do it to get to an in heat female. In heat females have been known to jump into yards to get bred. Friends or relatives are not always responsible about taking care of someone else's dogs, and often we hear stories about, the relative letting a friend visit with an in heat dog.
So if there is any concern, neuter around 6 months. The health benefits end up being a wash. With no testicles dog won't get testicular cancer. If your dog is left intact and runs off looking for an in heat female their chance of getting hit by a car is greater than the risk of any disease associated with getting neutered before 2 yrs of age. Plus an unwanted litter of puppies runs the risk of killing the mom, and the puppies being euthed when they end up in a shelter. So overall, the benfits of neutering outweigh the downsides unless you will never have your dog off leash or left unattended by you.
Our shelter has many stories of people bringing in unwanted litters by people that planned to eventually spay/neuter because they read that it is better for the dog, but then end up with an "oops" litter. The puppies end up killed. And if you search this forum, there are plenty of threads by people who planned to spay or neuter that ended up with an oops litter. It borders on irresponsible to encourage people to wait to spay or neuter, when the risk of an oops litter is all to real for the majority of your average dog owners, who DO put dogs in yards unsupervised, or have relatives/friends watch their dog, or whose dog isn't trained to never run out an open door.