You can start by adding major city and at the same time smaller surrounding communities.
We recommend adding no more than 5 cities with surrounding smaller cities.
But do not add a 6th city until you have all of your major and smaller cities to page 5 or less (4, 3, 2, 1) for major keywords. (the 1-2 keywords that get the highest search volume).
After you have 4-7 main cities ranking page one for main keywords, recall that Google will trust your site and future cities can rank very quickly with 0-3 basic backlinks.