Generally males should be neutered as close to a year of age as possible. Shelters will do it when they are far too young simply to prevent procreation. There are many different schools of thought on this, but one thing with which most people concur is that prior to six months of age is far too young.
It is thought, since males mature more slowly, that the longer one can wait (before they start marking and exhibiting other undesirable male behaviours) the better the chances are that their frames will develop i.e., broader chest and more masculine features.
This is a "nutshell" version that I am giving you, and as I already stated, there are many different opinions on this matter. I would discuss it with your vet, but please do not neuter prior to six months of age. Good luck to you.