I waited to neuter my male til he was about 1 year old. If I didn't have an intact female who could come into heat at any time (she is almost 11 months old and still no heat) I would have waited to 18 months to make sure the growth plates were closed first. There are risks and benefits to neutering. Neutering can mess with metabolism, can cause longer growth period, and cause thyroid problems. The main thing it can prevent is the rare case of testicular cancer. The risks of neutering however are far less than those of spaying which is why I chose to neuter my male and not spay my female....however...it is a personal decision as to what you choose, so good luck in the decision.