Pope Francis has invited all the Bishops of the world and their local Churches to participate in an Act of Consecration on March 25 to the Immaculate Heart of Mary.
“…I intend to carry out a solemn Act of Consecration of humanity, and Russia and Ukraine in particular, to the Immaculate Heart of Mary. Since it is fitting that we should invoke peace with our hearts renewed by God’s forgiveness, the Act of Consecration will take place within a Celebration of Penance to be held in Saint Peter’s Basilica at 5:00 p.m., Rome time. The Act itself will take place about 6:30 p.m.”
“…I ask you to join in this act by inviting the priests, religious and faithful to assemble in their churches and places of prayer on 25 March, so that God’s Holy People may raise a heartfelt and choral plea to Mary our Mother. I am sending you the prayer of consecration, so that all of us can recite it throughout that day, in fraternal union…”
For the celebration of Mass, it is most fitting that Mass texts be for the Solemnity of the Annunciation. Any other devotion you may wish to add after Mass, e.g., a recitation of the Rosary, may bring you to approximately the 6:30 time frame (1:30 Eastern Time in the USA). But please remember that the Holy Father notes that the prayer may be recited “throughout the day.”