I exported world I'm working on, and for now there are only 2 empty apartments and one park, plus all rabbitholes and ambitions lots, and almost immediately, mixologyst showed up, 3 paparazzi were hanging out, and a thief was reading a book, all in that one park. Later I saw some other Sims hanging out, so it won't be deserted world, only thing is you can't place premade families before exporting, but you can do what you want in edit town.