On 26 September 1988, the panchang shows Ashwin Krishna Pratipada — the 1st day of the dark half of the lunar month. ( drikpanchang.com)

In Jain practice, the tithis especially treated as auspicious or more observant are commonly Chauth, Ashtami, Chaturdashi, Purnima, and Amavasya; Pratipada is not usually counted among these special Jain tithis. ( jainknowledge.com)

So, for Jain purposes, 26 Sep 1988 was a normal tithi day, not a major special Jain auspicious day. ( drikpanchang.com)