Owned in DISS/JPAS vs. work dates?

When they say that your clearance must be active within 24 months to stay active, which date is checked, the work start date or being owned in JPAS?

Example:
If an individual’s clearance was inactive for two years on April 1st, but he was owned in JPAS before, and started work April 5th, would his clearance still be okay?