Hi Jesse!
From my understanding of the Transition Towns guides, you don't have to have official town status or anything, but you do need to identify your community and approximately how many people are in it. The idea being that whatever community you start building and transitioning, it will affect the surrounding communities.
They specifically state that in order to become official you must meet the criterion: "a recognition that although your entire county or district may need to go through transition, the first place for you to start is in your local community. It may be that eventually the number of transitioning communities in your area warrant some central group to help provide local support, but this will emerge over time, rather than be imposed."
https://www.transitionnetwork.org/support/becoming-official and the Transition Network (.org) website has a lot more information, resources, and guidelines in how specifically to build and achieve your community's Energy Descent Action Plan.
I love that they added "16. and finally, we recommend that at least one person on the core team should have attended a permaculture design course... it really does seem to make a difference."
I hope this helps answer your question, if you haven't found the answer already.