Whether you need a German certificate, and which level is required, depends on your purpose of stay and the specific visa process. The Federal Foreign Office lists telc as an accepted exam provider, but that does not create a general B1 requirement. Learn where to check the rules and how to find an external telc B1 exam.
Naturalisation involves two distinct areas: sufficient German skills and knowledge of the legal and social order and living conditions in Germany. Section 10 of the Nationality Act lists them separately. A B1 language certificate therefore does not automatically replace the knowledge test. According to BAMF, certain integration course certificates can cover both areas.
With changing shifts, a fixed study appointment may not always work. A realistic plan uses movable time windows, a short minimum session and a longer block on a day off. This example makes room for both German practice and recovery, without promising a set time to learn or reach B1.