Here are the two common understandings, depending on the Jain sect:

• Śvetāmbara (Paryushan for 8 days): The first day is focused on preparation and prayers. It sets the tone for self-reflection, vows, and seeking forgiveness as the festival begins. You may start with Amari Pravartana (resolution to practice non-violence) and Pratikraman as part of the day’s observances. You can read more here

• Digambara (Paryushan as Das Lakshan, 10 days): The first day is dedicated to the virtue Uttam Kshama (supreme forgiveness) and begins with the practice of forgiveness as a core discipline for the period. This day marks the opening of the ten-day focus on self-purification through forgiveness. You can read more about Paryushan observances here

If you’d like, I can summarize the day-by-day aims for both traditions in a simple chart.