My motto is "when you know better you do better" (or at least try to.) With this in mind, I am constantly reevaluating how I do things based on my current knowledge, whether it's from an outside source, or from my own experience. I am a lifelong learner, and I don't think I'll ever feel like I know everything there is to know about any specific subject, and this, of course, includes dogs as well. So, during the course of raising puppies, I changed my recommendation about when to spay/neuter a pup.
Some of my sources I can't cite because they came from conversations, but here are a few I can share that may start you off with your own research to help you make this very important decision for your own pup. The controversy surrounding the timing of these procedures comes from allowing your pup to fully develop into adulthood before cutting off the hormone supply required for proper development. Not allowing them to develop properly can not only translate to sub-optimal physical conditions later on but also behavioral issues. I leave it up to the owners to make their decision as they are the ones who will be living with and taking care of their dogs. I am only trying to pass on the information I now have.
Resources on spaying/neutering your pup...
2. On hormone-sparing sterilization with a directory of vets who perform such procedures (the closest ones to us are in Denver and Colorado Springs.)