Hmmm, I wonder where EWTN is getting their information from. I was mistaken and thought that the nine days of mourning began with his death, but then I received the newsletter from the Vatican Information Service which said:
SCHEDULE FOR NOVENDIALI, NINE DAYS OF MOURNING FOR POPEVATICAN CITY, APR 7, 2005 (VIS) - Archbishop Piero Marini, master of the Liturgical Celebrations of the Supreme Pontiff, has published a note on the "novendiali" or period of nine days of official mourning for the late Pope John Paul II, explaining the background and indicating the dates, times and principal celebrants of each of the nine Masses.
The communique states that "according to an ancient custom, for nine consecutive days there are special Eucharistic celebrations for the repose of the soul of the deceased Roman Pontiff, starting with the funeral Mass which is determined by the Congregation of Cardinals (cf. Universi Dominici gregis, n. 13 and 27)."
"Each day the celebration is open to everyone. It is, however, entrusted each day to a different group, taking into account that group's links with the Roman Pontiff. This variety of the congregation shows in a certain way both the milieu of the Supreme Pastor as well as the universality of the Church of Rome (Ordo Exsequiarum Romani Pontifici, n. 133)."
I was a little confused on that myself. Apparently, it all starts with the funeral Mass and is, indeed, nine days of funerals.