Write it down and you will be told.
A task app for Android, free, with no account, no subscription and no ads.
Tellcat is in a closed test on Google Play before its release. Join the test group with your Google account (the group page has no posts to show you, so look for the Join group button at the top), then opt in on Google Play and install it from there.
Every reminder is scheduled as an exact alarm. It survives the app closed, the screen off, the device restarted, and the clock or time zone changed. Snooze it or complete the task straight from the notification.
Reminder health checks notification access, exact alarms and battery restrictions, sends a test reminder when you ask, and tells you if a real one arrived late.
"Call mum tomorrow 6pm" schedules for tomorrow and sets a 6pm reminder. What was understood is marked before you save.
No account, no sign-up, no servers. Tellcat does not request internet permission, so the app itself sends nothing anywhere.