Why did 2 temples in MP celebrate I-Day on Aug 11 instead of Aug 15?

Two famous Madhya Pradesh temples—Mandsaur’s Pashupatinath Temple and Ujjain’s Bade Ganesh Temple—celebrated Independence Day on August 11, four days before the national celebration. The temples follow the Hindu calendar, marking the occasion on Chaturdashi of Shravan Krishna Paksha. Priests said August 15, 1947, corresponded to this date in the Hindu calendar. This year, it fell on August 11.