See the Excel file on course selection for information and details.
Most courses can be decided on at the beginning of the lecture period. Only very few courses have the requirement of a sign-up beforehand. Most courses you just attend the first session. Only exams require a registration (which is mostly during or at the end of the lecture period).
See section NTNU → Grade acknowledgement; Courses and grades on diploma and transcript TUB / NTNU on how to get courses taken at TUB approved at NTNU to get the NTNU diploma.
See section THESIS directly hereunder on how to get the thesis taken at TUB approved at NTNU to get the NTNU diploma.