My Rott was neutered at 6mo. I got him it 8ks old
It was a condition of adoption that was set by the rescue group. They were very adamant about it - they sheduled the appointment for me with their vet (& paid for it) - there was no negotiating it. He grew to be average height & size for a Rott.
My mom's lab was neutered at 1yr (also adopted). It didn't stunt him at all - he's HUGE (& not it a fat way either)! Approx. 27" & 110#... see photo below
Unless you intend on breeding - for the "betterment of the breed" - go ahead & get the snip.
BTW - for perspective, those are 18" floor tiles