I overlooked the fact that it was the creation-date-time of an object you wanted.
If the create-date-time is not a part of an object (I don't know if it is or not...) a workaround would be to do some administrative housekeeping yourself.
1) At regular intervals run a query (SQL, ARS-API or whatever)
2) The query lists the existing objects and stores the information "somewhere".
3.1) Then you could do some aggregation on the raw-values like only store the time when objects are created and deleted.
3.2) Or you could keep the raw-values (but this can mean lots of data if the interval is short).
4) With this in place you should have the framework for creating the reports you want.
5) If you can't report on the information you have directly, then you might have to "twist" a bit on the datacollection (1-3).
Once again, I don't know if the create-time of an object is stored somewhere internally. Could be worth to dump a single AL to a def-file and check the contents of the export-file.
I hope I have thrown a few ideas into the air....
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Quick