It will take maybe a week before it drops. I leave mine in the charger but not plugged in. Mine have discharged but I can’t provide a time line. It’s good they discharge. Sometimes I use the batteries to charge other devices if I’m not flying much.
One thing I am more uncertain about is whether the batteries will discharge if they are in their dock and that dock is plugged in. Mine has been in that state for more than 24 hrs and my packs are still 100%.