Best practice for breeding was to wait until a dog was at least 2-4 years old, had at least 3 heat cycles to breed, and also to skip at least 1 cycle between.
They recommended getting him desexed after 6 months. I've read that getting them desexed too early can increase the risk of hip and elbow dysplasia by 3 times.
If your dog has already begun to have seasons, your vet will normally recommend waiting 12 to 16 weeks from the start of the most recent season before spaying.
We recommend waiting until your dog is at least over 6 months and likely even older for larger dogs. The benefits are much more pronounced in larger dogs.