The traineeship should preferably be completed after the first year of study of your Bachelor's program. The second year is another possibility. After the first year of study you will already have some insights into the subject of Geography while you still have the option to adapt your studies to the requirements of the job market. After the second year of study, the best synergies for subject selection with regard to the Bachelor's thesis are given, but you will have to take into account that the field trip of the regional module generally takes place immediately after the 4th semester in August or September.
The Master's course is similar: Here, the traineeship can be largely integrated into the personal study course, but should not be take place too early or too late.