Getting your puppy fixed is one of the most important thing you will do for your dog. It is debated whether it is best to get them fixed before or after puberty, but I find the argument to get them fixed early much more sound. Most vets recommend getting a puppy spayed or neutered between four and six months. In female dogs, spaying them early will eliminate the risk of ovarian cancers and cysts, and lessen the risk of mammary cancer. In male dogs, neutering them early will prevents testicular cancer and lessens the risk of some prostate diseases. In addition to the health benefits, fixing your puppy will help prevent behaviors that are undesirable in your pet. Females won't go into heat, which means you won't have to deal with the vaginal discharge that can last up to two weeks. Males are less likely to display behaviors such as marking (peeing on anything and everything), humping (anything a everything), and dominance behaviors such as aggression. On its base level, fixing your animal will prevent more puppies from entering your community. Shelters are already bursting with dogs of every shape size and color. Even if you think it would be cute to see your dog's puppies, it is more important to the health and happiness of your dog that they are fixed as recommended by breeders, shelters, and veterinarians. I will link an article about the importance of spaying/neutering your puppy.
An inclusive checklist for bringing home a new puppy (straight from the mouth of a dog bather, vet tech student, and dog lover all in one). I linked many informational articles as to why you need these things, and what considerations you should make when choosing your new puppy supplies.