When is Dhamma Chakra Pravartan Din 2028? Wednesday, 27 September

Each year on this day, well over a million people gather at Deekshabhoomi in Nagpur, the stupa raised on the conversion ground, to pay respects, take the vows, and re-affirm the path. Vandana and Dhamma talks, the reading of Ambedkar's 'The Buddha and His Dhamma', book stalls and social gatherings fill the day. It is observed at viharas and Ambedkar Bhavans across Maharashtra and beyond.

Ambedkar, the jurist and principal architect of the Indian Constitution, had declared in 1935 that though born a Hindu he would not die one, seeing no path to dignity for the so-called untouchable castes within the caste order. After two decades of study he chose Buddhism as a rational, egalitarian and Indian tradition. He converted at Nagpur, a site linked to the Nagas said to have spread the Dhamma, seven weeks before his death on 6 December 1956; 'The Buddha and His Dhamma', published in 1957, became the movement's book.

Source: Wikipedia — Dhammachakra Pravartan Din

The 1956 conversion made Buddhism a living Indian religion again after centuries; the 2011 census counted most of India's roughly 8.4 million Buddhists as Navayana followers, concentrated in Maharashtra. 14 October and the associated Vijayadashami date are kept as major days; the Deekshabhoomi gathering is among the largest in India.

• Wikipedia

1. Lakhs of people gather at Deekshabhoomi in Nagpur, where Dr B. R. Ambedkar took Buddhism on 14 October 1956, to pay homage at the stupa.
2. The Three Refuges, the Five Precepts and Ambedkar's twenty-two vows are recited, and many take diksha on the day.
3. Book stalls, speeches and cultural programmes fill the grounds, and Buddhist families across Maharashtra hold gatherings at home and in viharas.

• Nagpur (Deekshabhoomi). Over a million gather at the stupa for vandana, the taking of the Three Refuges and the twenty-two vows, and Dhamma talks.
• Maharashtra and across India. Observed at viharas, Buddha Vihars and Ambedkar Bhavans, with processions, the reading of 'The Buddha and His Dhamma', and social gatherings.

• Bhojandan — Volunteers run free food stalls for the pilgrims at Deekshabhoomi.

Dhamma Chakra Pravartan Din is kept on the day when Dashami of Ashwin Shukla paksha prevails in the Aparahna (afternoon). That day is Wednesday, 27 September 2028. Dashami holds the whole of the Aparahna (afternoon) on this day. It holds none of it on the day before or the day after.

in the Aparahna (afternoon)

Kept on 14 October, the anniversary of the 1956 conversion, and on Ashvin Shukla Dashami (Vijayadashami), the day on which the conversion took place in 1956 and which Ambedkarites call Ashoka Vijayadashami. Other Buddhist observances, such as Buddha Purnima, follow the full moon of the lunar month.

A lunar date: Dashami of the bright half of Ashwin drifts about 11 days earlier each solar year, then jumps back ~19 days when a leap (Adhika) month is inserted.