Book the Anmeldung before you unpack

Almost everything else in Germany waits on the Anmeldung. Your tax ID is posted to your registered address. Most banks want the confirmation before they open an account. The Ausländerbehörde will ask for it at your permit appointment.

So the first thing to do, before the boxes are even open, is book the appointment. In Hamburg the slots release in batches and the good times go fast. Have your passport, your rental contract, and the Wohnungsgeberbestätigung from your landlord ready on the day. Miss one of those and you start the queue again.

If you cannot get an appointment inside the two-week window, that is normal and not a fine in practice as long as you booked the earliest slot available. Keep the confirmation email as proof of when you tried.