PM Report Request

We are using CAM in 9.2.  Seemingly simple user report request:  For a specific time period (month), what PM WOs were generated, how many were completed on time, how many were completed late, and how many are still open.

The PM WO created date and completed date are straightforward, but they alone won't tell you if the PM WO was completed early, late or on time.  Assuming that >100% due is late,  what is the best way to get an accurate % due for the date that the PM WO was completed?  For instance, two PM WOs, each with same created date 11/12, but different completed dates 12/31/18 and 1/4/19.  Both entered on 1/4/19 (one backdated and one entered same day).  When I run R12807, both are updated to % Due of 280, which will present an incorrect picture