I beg to differ and think it is up to you unless there is a medical reason. Neutering does not change behavior; training does. If there is no medical reason for it and your dog is not roaming the neighborhood, I'd cancel the appointment for his health.
Some of the reasons they will give to neuter is that it prevents prostate cancer. That would be like amputating his leg so he won't be able to break it.
Definitely agree with this. If you have control over your dog and there's no risk of a mistake or unwanted breeding, I don't recommend neutering. Particularly before 2 years. If you do want to neuter, for whatever reason, at least wait until the dog is 2 years old. Right now, at 19 months, the dog is still growing and he needs those hormones.
MacKenzie - Workling Line Female (In Loving Memory)
Wolfram - West German Showline Male [SG1, CGC, DDN, CN, EN, IN, VN]
Bash - Working Line Puppy