Duke was around 10 months when I got him neutered, wanted to do it earlier as everyone rec'd 6 months but was not able to. I think it was fine still. He took a few short days before he was back to his active self.
I don't think his personality changed at all. He still lift his leg when he pees on the pad or outside
. He also still hump his stuff animal girlfriend
but I heard that it's ok that he does that.
Duke also got his chip the same day too and I was able to bring him home with me later that day. I would say that someone should be with him all day for the first few days to monitor him especially with the cone around their neck.
Good luck.