The cardinals will first gather on May 7 at 10am local time (6pm AEST) for a mass known in Latin as Pro Eligendo Romano Pontefice (For the Election of the Roman Pontiff) in St Peter's Basilica in the Vatican, the announcement said.
At 4.15pm (12.15am AEST), the cardinals eligible to vote will assemble in the Pauline Chapel in the Apostolic Palace, from where they will process into the Sistine Chapel at 4.30pm.
The Vatican did not initially provide further details.
Traditionally, however, the cardinals must, after the solemn procession, swear an oath to observe the conclave's rules and maintain absolute secrecy about the election.
The master of the papal liturgical celebrations then calls out "extra omnes" (everyone out), instructing all non-electors to leave the chapel.
The process for the first ballot on the first day is already clear. The subsequent schedule consists of two ballots in the morning and two in the afternoon.
For a new Pope to be elected, a two-thirds majority of the voting cardinals is required, and there is no time limit for the conclave.
Two cardinals will be absent from the conclave for health reasons, Vatican spokesman Matteo Bruni said on Tuesday local time.
A total of 135 cardinals are eligible to vote in the conclave. After the cancellations, there are now only 133 who will vote from May 7.
Bruni did not name any names, but the emeritus archbishop of Valencia, Antonio Canizares, 79, stated a week ago that he would not be able to travel to Rome for health reasons.
The emeritus archbishop of Sarajevo, Vinko Puljic, 79, had excused himself for the same reason. A few days after his cancellation, Puljic told the broadcaster Radio Medjugorje that his doctor had then allowed him to travel.
Disgraced Cardinal Angelo Becciu has backed down in the dispute over his participation.
"I have decided to obey - as I have always done - the will of Pope Francis not to enter the conclave, while remaining convinced of my innocence," a personal statement from the Italian said on Tuesday.
Becciu's announcement of his intention to participate in the conclave, despite his involvement in a financial scandal, caused a stir in the runup to Francis' funeral.
In 2020, Francis stripped the 76-year-old of the rights associated with the cardinalate in the wake of the major fraud scandal.
His exact status has not been entirely clear since then, but Becciu was listed as a "non-elector" in a Vatican list for the conclave.
He said he made his decision to withdraw for "the good of the Church", the Sardinian-born cardinal wrote. He said he wanted "to contribute to the communion and serenity of the conclave".
At the end of 2023, Becciu became the first cardinal in the history of the Catholic Church to be sentenced by a Vatican court to a prison term of five years and six months.
The trial involved questionable multimillion dollar deals in a real estate scandal in which he was implicated.
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