The Divine Mercy novena begins today (Good Friday) and ends on Divine Mercy Sunday (the Sunday after Easter).
The devotion to Divine Mercy is a powerful one, and it has spread far and wide through the Church in a very short time.
I once visited the convent in Krakow, Poland where Saint Faustina Kowalska lived and prayed. Saint Kowalska is the nun who received the devotion to the Divine Mercy in a series of private revelations from Jesus in the early part of the 20th century.
Wishing you a blessed Triduum and a happy and holy Easter!