The first entry in the baptismal register for Beagle Bay is for Felix’s baby, Maria Norengbor. During August 1896, 12 Nyul Nyul men were prepared by Fr Alphonse and baptised with great solemnity at Beagle Bay by Abbott Ambrose. Each retained his traditional names, but took as baptismal name, that of one of the trappist monks (Sebastian, Joseph etc). From this time on baptisms were recorded regularly both at Beagle Bay and Disaster Bay Missions.
Main Source: http://wkfl.asn.au/religioused/beagle_bay_church_history.htm (Author Frank (later Father) Birrell).
Photo: From diocesan website around 1890s
the French Trappists invited the media in August 1896 to witness the baptism of their first 12 young men at Beagle Bay. To the Indigenous or accepted names of the candidates they added their own personal names (Sebastian, Narcisse, Joachim, Joseph, Jacques, etc.). This must have set a strong signal of relatedness between the baptised community and their namesake Fathers and Brothers. In 1897, another 23 gathered for mass baptism, and altogether the Trappists claimed to have baptised over 200 people.30 This means that the following three years must have seen a veritable rush into this new ceremony with an average of over 50 each year.
Cited from: https://press-files.anu.edu.au/downloads/press/n4239/html/ch04.xhtml?referer=&page=7
Brian McCoy says the day was 25 August.
In his history of Beagle Bay, Frank (later Father) Birrell wrote: Up to August 1896 the only name in the baptismal register was that of Felix’s baby, Maria Norengbor, but from this time on baptisms and marriages were recorded regularly at both Beagle bay and Disaster Bay (near Lombadina) missions. In October, Brother Xavier wrote to Bishop Gibney on the occasion of the first twelve members of the Nyul Nyul tribe being received into the Church by Abbot Ambrose. Father Alphonse had instructed them all.
Cited from: http://wkfl.asn.au/religioused/beagle_bay_church_history.htm