In Jainism, Diwali is observed to commemorate Mahavira’s Nirvana. The key point is that the exact day (tithi) and timing differ between Digambar and Shwetambar calendars and between local temple calendars. Because of these calendar differences, there isn’t a single universal “best time.”

• General idea: most Jains observe Diwali around the Kartik month, when Mahavira’s Nirvana is remembered, with practices like mindful puja, lighting lamps, and visits to temples.
• Digambar vs. Shwetambar: the specific tithi and ritual emphasis can vary between the traditions. Some communities mark the Nirvana day on a particular tithi in Kartik, others align with the surrounding festive program at their temple.
• Practical guidance: check your local Jain temple or community calendar for the exact date and recommended puja timing for this year, as it will specify the precise tithi and time window (often a morning or evening puja, sometimes a pradosh period).

If you’d like, I can look up the current year’s Digambar and Shwetambar Diwali/Nirvana-day timings from Jain calendars and share the exact date and suggested puja window.