Das Lakshan Parva (Dash Lakshan) begins the day after the Samvatsari. For 2025, it is observed to start around August 28, 2025 (some communities begin on August 27, 2025, depending on local calendar) and lasts for ten days, ending on September 6, 2025. If you need the exact local date for your temple, check with your community calendar. You can read more here