Hello to you and your adorable pup whose name we don't know unless his name is Lydia (and I don't think it is!) He's awfully cute! I think many of us who own males have waited to have them neutered until they are 18-24 months of age. Mine was neutered at 3 years old. We didn't have any trouble with behavioral issues related to him being intact but our contract with the breeder included that we had to have him neutered at some point. She wanted us to wait until he was at least 2 y.o. so we did.
There are legit reasons some people have to neuter younger, they can't find any kennels or day cares that accept intact dogs being a big one, if they have to use day care or kennel their dogs. There is a thread with a lot of articles regarding spay and neuter and deciding when the best time is. Many vets will advise a neuter at 4-6 months. One vet in the practice we use got a little pushy about it, too, but the main vet didn't opine one way or another. I thanked the first vet for her opinion and didn't schedule any further visits with her. So there!
Ours potty trained pretty quickly, too. Not everyone is as lucky. Sounds like you're doing a good job!