In Jainism, Rai Pratikraman (also spelled as "Ratri Pratikraman") refers to the evening Pratikraman ritual, which is a practice of repentance, reflection, and spiritual cleansing performed daily by devout Jains, especially in the Shwetambar tradition.

Timing for Rai (Ratri) Pratikraman:

• The Rai Pratikraman is traditionally performed after sunset, once the day’s activities are concluded.
• Ideally, it should be performed within 48 minutes after sunset (this period is called "Sandhya Kaal" or twilight).
• The exact clock time will vary depending on your geographical location and the time of year. Jain calendars or local Jain temples often provide specific timings for your area.

Day 1 refers to the first day of an event or a festival (such as Paryushan or Das Lakshan). On such days, Pratikraman is performed in the evening as per the above timing.

Summary: Rai Pratikraman on Day 1 should be performed after sunset, ideally within 48 minutes of sunset, following the guidance provided by your local Jain temple or calendar.

If you need the exact time for a specific location and date, please consult your local Jain sangh or Jain calendar.