Do not just dump 100 MP3 files into one folder. Organize them by chapter (Lektion 1, Lektion 2, etc.) and by book type (KB for Kursbuch, AB for Arbeitsbuch). Example: German_Sicher_B1 > Lektion_1 > KB_Track_01.mp3

To avoid overwhelm, here is a realistic weekly schedule.

Without the audio, you are essentially learning to read and write German in a vacuum—a recipe for failure when faced with a real conversation.