
I take it that your female pup is a GR as well?
It's redommended that you leave spaying until approx 18 months in order to allow her to finish growing and that the growth plates have closed. Goldens are a bit slow to mature and really need that extra time.
I've had four. First one was spayed after her first season as the vet recommended this. The next two were spayed before their first season, again recommended by the vet I was seeing then, but both were about 10 months when it was done. The one I have now was spayed after her first season as close to 18 months as I could get her. I ended up needing to get her spayed a little earlier then I intended as she was going to stay with her breeders for 6 weeks who have a number of male dogs all very closely related and I didn't want her coming into season there which seemed highly likely.
The two that were spayed early did have some issues. Older dog was tall and rather leggy and her hind legs were straighter then normal. Younger dog did have a crusciate repair when she was 8, whether this was due to early spaying or other circumstances is unknown.
I was pushed to spay my current dog by a locum working at the vets, but I firmly told her that she would be having at least one season before that happened. My normal vet lets me make up my own mind and doesn't push me one way or the other.