The College of Cardinals will start its conclave to select a new pope April 18th.
A Vatican spokesman says the cardinals made their decision after reading Pope John Paul II last will and testament.
The text of that document will be released publicly Thursday. U.S. President George Bush and his wife Laura left Washington Wednesday to attend the funeral.
A Vatican spokesman says the cardinals will celebrate a morning mass on April 18th, and then will be sequestered in the Sistine Chapel in the early afternoon to start the conclave.
The decision on a date came on the third day of meetings of cardinals. One hundred seventeen cardinals will cast ballots for the next head of the Roman Catholic Church.
Two ballots are held each morning, and two each afternoon.
The Vatican also announced a major change to the centuries-old practice of signaling when a new pope has been chosen. Following each vote, ballots are burned in a stove in the Sistine Chapel. The Vatican sends up black smoke if no decision has been made. White smoke means a new pontiff has been chosen.
This year, bells will also peal in St. Peter's Square when the pope is chosen.
That's because there was confusion, when John Paul was appointed in 1978, about whether white or black smoke was seen coming from the chimney.
Meanwhile, hundreds of thousands of pilgrims continue to file past John Paul's body as he lies in state in Saint Peter's Basilica. An estimated 600,000 people viewed the body Tuesday.
Many stood in the cold -- in lines up to two kilometers long -- for as long as 12 hours, to catch a glimpse of the late pontiff. Once night fell, many in the crowd huddled under blankets to keep warm. A few lucky people managed to find beds at a makeshift accommodation center set up nearby.
Preparations continue for Friday's funeral. Crews have begun assembling a giant television screen for pilgrims to watch the ceremony. Medical emergency tents are also being set up nearby. Authorities say Rome will close public offices and ban cars from the streets Friday to make way for an estimated crowd of more than two million people.