It's largely a matter of to what degree a congregation can support itself independently. The first step is often Mission Group status which is often born from a Sabbath School class at another church, or a group of people in a region who want to worship at a convenient location. At some point, a Group is able to support themselves via tithe and offerings to a limited degree, show progress with evangelistic effort, and qualify to organize as a Company with sponsorship of a parent church. Upon the ability to operate fully independently and meet certain other criteria, the congregation can qualify to organize as full Church status. The amount of time it takes to progress from one status to another is entirely up to the congregation. It could be many years. Or, in some cases, a group of people had sufficient resources to organize into a Company almost immediately, and as a Church in about a year.