In Jainism, particularly among the Digambar sect, Daslakshan Parva (also known as Paryushan Parva or Das Lakshan Mahaparva) is a very important annual festival. It is a ten-day period of intensive spiritual practices, reflection, and celebration of ten main virtues (Dashalakshana Dharma).

Start Date: Daslakshan Parva begins on the fifth day (Panchami) of the bright fortnight (Shukla Paksha) of the Jain month of Bhadrapada, immediately after the conclusion of the Shvetambar Paryushan festival (which ends on Samvatsari). The corresponding dates in the Gregorian calendar vary each year, usually falling in August or September.

How to know the exact date: To find the exact starting date for any particular year, refer to a Jain Panchang (calendar) or consult your local Jain temple, as the dates are determined according to the lunar calendar.

Summary:

• Daslakshan Parva (Digambar Paryushan) starts on Bhadrapada Shukla Panchami.
• It generally falls in August or September.
• The exact date changes each year based on the lunar calendar.

If you need the specific date for a particular year, please mention the year, and I can provide more detailed information.