We recommend letting your Shiba mature past the puppy stage prior to alteration. Plan to have the procedure done at around 1 year of age. We strongly discourage altering females prior to/ during their first heat (usually occurs around 6 months of age), and males should be at least 9 months old. There are many benefits to allowing your Shiba to mature prior to spay/ neuter, including lower cancer risks, joint health, bone growth, coat health, etc.
More information can be found here:
https://www.akc.org/expert-advice/vets-corner/neutering-spaying-right-age-dog/
Putting aside the obvious answers- health testing, good temperaments, socialization, and breeder support, let's talk about why you want a Shiba instead of just a "dog", or a lab, or a chihuahua. You want the look and personality/ traits of a Shiba. It's what draws you to the breed. Show breeders will be intentionally producing that.
https://www.akc.org/expert-advice/dog-breeding/why-buy-from-a-responsible-breeder/