One is not obligated to put up mezuzahs before they begin to live there/ work there, even if they already moved in their belongings.  Similarly, the 30 days in chutz la’retz begin from when one starts to live there not from when they move in their belongings.  Although in chutz l’aretz one has 30 days before needing to put up mezuzahs, the minhag is to put the mezuzahs up right away when moving in. Rav Moshe writes that one should place them as soon as they move in, but wait to say the bracha until day 30, and then move the mezuzahs a little.