The bachelor thesis represents the completion of the bachelor program. It is intended to prove to students that they can independently work on a specific scientific question. The bachelor thesis is the last module in the curriculum and can only be officially registered once the necessary credit points have been reached and all other modules have been completed. Of course you can already plan your bachelor thesis during your studies and look for a suitable topic and supervisor. It makes sense to have already done some preliminary work before registering the work. Because there are usually only a few months to complete the work, so certain things should be clarified in advance. These include the choice of topic and the vote of the same with the supervisor.
The research of the necessary literature and sources, and not least the rough planning of the time and content of the bachelor thesis, should take place before the actual registration of the work in the examination office. This ensures that there is enough time to write and correct the thesis during the actual editing period.