DATEDIF (), which means Date + Dif, is a compatibility function left over from Lotus 1-2-3 that Microsoft adopted in Excel version 2000. It's fallen off current Excel menus, but you can still use it.

You can create and set the trigger for an alarm in MS Excel by creating a VBA module. Learn how to Ring an Alarm in Microsoft Excel.

Using Excel as a scheduling tool is a great skill to have under your belt. Learn how to use SUM, DATE, WEEKDAY, IF, Nested IF, and IF/OR functions.