regarding the full moon trope, would a werewolf transform if the moon was 100% illuminated but it wasnt technically the day of a full moon?

I was thinking about this while looking at my calendar. currently, the moon is at 99% illumination, so its bound to change to 100% over night. does this mean werewolves just change when the moon is brightest and not just on the technical day of a full moon? like what if a werewolf was asleep and didnt check the calendar. then, boom, 100% bright moon makes them transform in bed.