When a geocacher is preparing to publish a new cache they enter their information onto the new cache form, double check everything is correct and then submit it. The form is stamped with a "Placed" date. Many times the cache is not published for a day or two and sometimes longer than that if something needs to be corrected before publication. The challenge of this cache is to record 10 previous finds that show this date discrepancy in a progressive order. The finds and dates do not need to be progressive, just your report.
EXAMPLE A: Geocache 'ABC' was placed on 3/1/12 but not published until 3/4/12. This would qualify for a cache with a 3 day difference.
Example B: Geocache 'XYZ' was placed on 2/1/12 but not published until 2/9/12. This would qualify for a cache with an 8 day difference.