Is there a way to set up a date calculator between two date columns?

I have two date columns-- one with dates in the past, one with dates in the future.

Is there a way to set up an automation that notifies me if the future column, when the date is entered, is a certain number of months after the before date?

I.e. Before date is March 2, 2020. After date is July 17, 2023
I need a notification, when that after date is entered, that tells me if it is 24 months between the two dates or not.

I also need this notification 30 days before the after date, to make things more complicated, lol

Thanks!!