Hello KNA,
It's a great idea I have not done yet.
We are able to see that date properties are only text (system date are different) :
And there is no property values about date.
So I think you should create your own hour, day, month, year properties to be able to calculate them.
Christophe - FRANCEArchicad Designer and Teacher
Archicad 15 to 27 FRA FULL
OS 11.6 Big Sur - MacBook Pro 2017 - 16Go RAM
"Quality is never an accident ; it's always the result of an intelligent effort" John Ruskin