You can always start it if no one is there yet. Might be best to do it for the phases, or even a smaller neighborhood area, because the info means more to you if its about an area near your house. I think they usually go by zipcodes when they choose who gets included in each area. Somtimes more than one zipcode is together. I've been in 2 different sections of Los Angeles on Next Door. They dont allow you to be in 2 places at the same time and youre suppose to use your real name.
Ok you made me look. I see my SC neighborhood of Dawn Lake already has its own NextDoor so they will keep it to a small neighborhood area. Good to know.