Well, for the religious this is Passover Week. For those purchased with the blood of Jesus, every day is Passover because Jesus is our Passover.
According to the scriptures, Passover was already being observed (John 12:1 for example). But, if you will read I Corinthians 5:7 it says: "Purge out therefore, the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ, out Passover, is sacrificed for us.
The word says to purge out the old leaven. The Church is to be a new lump, following the teachings of Jesus Christ. Jesus did not teach to observe days.