Finally, I added all the features my housemates had designated essential. Precisely one month after the initial deadline, I had my first users.
There where a lot of problems at first. I clearly hadn't tested enough. Various GUI elements broke because people's names where too long. Safari users couldn't log in, while Edge users would be randomly logged out when performing certain actions.
At this time, I was hosting on pythonanywhere and everything ran horribly slow. Various buttons and features did not actually do anything. There was no way to log out. Database was SQLite. Overall not really suitable for production.