For the patent approval In united state it takes from one year to 3 years and sometimes it could be more in some cases, but the inventor usually apply for the priority so they can accelerate the process and reduce the duration. 

  Perhaps the inventor can start selling the products    but the purpose for patent approval is:    the patent owner has the exclusive right to prevent or stop others from commercially exploiting the patented invention. In other words, patent protection means that the invention cannot be commercially made, used, distributed, imported or sold by others without the patent owner's consent.   When the patent status is no longer pending. Your invention can no longer be produced or sold without your consent. You should mark a patented invention with "patented" and the patent number instead of "patent pending."

Although i am not so sure about these info and even it could something else only doctor chris knows what’s going on 🤷‍♂️