Am a keen follower of Microsoft's SharePoint Blog and proud to provide this direct from the Microsoft Tech Community:

Personal productivity is essential to teamwork.  SharePoint lists and libraries have long allowed to you defined custom metadata columns to track dates.  As announced at Ignite 2018, we are releasing a new capability that lets you set reminders for any of these dates.  You’ll be able to receive a personal email alert ‘x’ days in advance of a date on any document or item in SharePoint.

Create a reminder flow

To create the reminder flow, your list or library should have at least one date/time column in the current view. You’ll then able to create a reminder by selecting the Flow->Set a reminder menu.

You can enter the number of days in advance for the reminder, based on the selected date column.

Based on your selection, you’ll get an email from Microsoft Flow for any items or documents ‘x’ days in advance of the selected data column value.

Once the flow is created, it can be edited from the Microsoft Flow website. You can modify “days in advance”, or add additional actions.

This feature is slated to begin rollout to Targeted Release on or about December 18, 2018.  If you’d like to try it in advance, you can see reminders in action on the Business Apps Resource Center.

As always, we are listening for feedback.  Please let us know if you have any questions or suggestions.  Thanks.

The above is kindly provided by the Microsoft Tech Community!