Is it possible to extract when the user access has been granted to all empower user? How?
I would imagine the easiest way would be to pull up the system audit trail and create a view filter for the "Created User" event. You should then get a slimmed down audit trail which would list this info. I have a generic filter to sort by action that allows me to simply select the action to filter.
For a generic filter, enter "=#" in the "Action" column and include the "Change Date" and "Details" columns. The details column will include the user's name, so between these 3 fields, you can identify each user and the date/time the account was created.