Phase 3: The Schema

Design and build your schema. Every table with a comment saying what one row represents, every relationship with a deliberate on_delete and a one-line reason, and every constraint you can justify. Create the custom user model now if there is any chance you will need one. Then load realistic test data, at least a few hundred rows, and write the five queries your application will run most. Do not index anything yet: you will do that in phase 7, with the plans in front of you.