Our first dog was required to be neutered before going home... he was probably around 3 months at the time. We got him at the local humane society, no room for negotiation.
He grew into a 199lb mutt (breed guess: rott/GSD/Pyrn). He did suffer from some arthritis in his later years (starting around 7 years or so... he died of cancers at 8.5yrs), but otherwise, we didn't notice anything (but that could have been because we weren't looking, too).
Not sure if the early neuter had any other effects. The cancers that took him were everywhere, and we fed many years of poor quality food before we knew better... so lots of blame to go around.
I'd want to wait as long as you can to provide the best growth and health potential... but sometimes that's not an option, and you just have to roll with it if you find that's the puppy for you.