Adding the created date as the start date for the google analytics query...

... and adding an earliest cut off for older systems who were not collecting google analytics in the past.

Why the earliest analytics date:
If you were not sending download statistics (that were not included before sufia 4.0) to the system you may want to not say the statistics are valid since when the files were deposited.  Instead you may want to say for older files that the statistics are valid since the time you started keeping track.
@mjgiarlo Added a test for a blank earliest date.  Rearranged the test a bit, but not sure if I need/want to move the allow_any_instance out of the let.