Jackson was 7 months old when neutered. He was a bigger boy and by 7 months old was around 12lbs. He lifted his leg once on my dad's outdoor porch furniture and I went
uh-oh! and scheduled the neuter for the following week. He was pretty much fully matured (he stayed at 12lbs up until around 3 months ago... where the last vet scale claimed he's 16lbs, but it's mostly muscle because he didn't outgrow anything). It worked fine for us
IMO, between 6 months-10 months is a
great time but it all depends on the dog. He also had 4 baby teeth pulled that were not coming out (his canines) and was microchipped. If a dog was already marking or humping a lot, etc, I would neuter asap to prevent habits.