Currently you provide a link to the JSON data, then this is fetched and stored locally forever. Need to add some sort of mechanism to update this once in a while.

Ideally the app will keep track of when the saved timetable has last been updated, if it hasn't been updated in e.g. a week the app should fetch again from the link and update the saved timetable if it is different. Maybe use a hash for this.

If auto update is enabled in settings, have a check done on app startup to see if timetable is older than seven days, then display a popup/toast in the bottom right asking if they want to refetch the timetable.

Cool feature might also be to try refetching anyway and compare the date of the new timetable to the old one first, then you could say "Newer timetable available, refetch?".

If timetable is old you could display a warning somewhere, this could be optionally hidden using a setting.

Sometimes the tab for the day doesn't switch to the current day, even though the correct day becomes bold

App is definitely usable but there is a little lag, not sure what is causing this.

The JSON has details on the timetable including course etc. but they currently aren't displayed anywhere. Could display this somewhere, even just in settings or for debugging purposes.