So, it took about 2.5 weeks exactly to get the results of my citizenship test. This is definitely a "your mileage may vary" thing. A British colleague of mine who is also pursuing German citizenship had to wait around 4 weeks.
I'm pleasantly surprised, because I know there were at least 4 questions that I was really uncertain about . I'm also not surprised, because this was also within the range of the practice tests that I took.
Fazit (as the Germans say): Go through the BAMF interactive question catalog completely at least once. Get a free app with all of the questions (here's the Android app that I used). Preferably one that structures the practice tests like the real test (i.e. 30 questions about Germany, 3 questions about your German state) and then just do it 'til your regularly getting like 20 or so correct all the time.