What day of the triduum do we celebrate the founding of the eucharist?

The founding of the Eucharist is celebrated on Holy Thursday, which is the first day of the Triduum. This day commemorates the Last Supper, where Jesus instituted the Eucharist by offering bread and wine as His body and blood. It is a significant moment in the Christian liturgical calendar, marking the beginning of the Paschal Triduum leading to Easter.