The first week does not need to contain every bureaucratic task. Start by making your address usable, confirming time-sensitive obligations and creating a dependable way to receive messages.
On the first days
Learn the route between your accommodation and work, understand the fare zones you actually cross, and put your name on the letterbox if permitted. Confirm any booked appointments and check the required originals.
Keep one folder for official letters and record the date each arrived. German correspondence often states a response deadline. Translate for understanding, then seek an appropriate professional if the matter concerns law, tax or health.
Leave room for ordinary life: buy only the household basics, walk the neighbourhood in daylight and note the nearest pharmacy and grocery options. Familiarity reduces decision fatigue more effectively than a packed checklist.