There is a way to do this presently, I believe.
Go into:
Tools->Options
Then select:
Themes and Formatting
Then click:
Data and Time Format...
Then (and here's the secret bit). Click
Advanced tab
Play around with the settings in there. Inserting R into the date format will give you a relative date (e.g., nnn days ago)
I think you can get it to what you're looking for.