Faulty translatiuon has created a misunderstanding;
1. the word "day" is supplied, and is not in the Greek text.
2. The greek word "protos" is used as first as in before and as first
Matthew 26:17
New International Version
On the first* day of the Festival of Unleavened Bread, the disciples came to Jesus and asked, "Where do you want us to make preparations for you to eat the Passover?"
“first” is word #G4413. prótos
Strong's Concordance
prótos: first, chief
Original Word: πρῶτος, η, ον
Part of Speech: Adjective
Transliteration: prótos
Phonetic Spelling: (pro'-tos)
Short Definition: first, before
Definition: first, before, principal, most important.
John 1:15 Adj-NMS
GRK: γέγονεν ὅτι πρῶτός μου ἦν
NAS: than I, for He existed before me.'
KJV: for he was before me.
INT: has for before me he was
The Passover was not until the following day, this is fact;
John 13:1, “And before the Festival of the Passover, יהושע knowing that His hour had come that He should move out of this world unto the Father, having loved His own who were in the world, He loved them to the end.” TS 2009
John 13:1, “Now before the Feast of the Passover, when Jesus knew that his hour had come to depart out of this world to the Father, having loved his own who were in the world, he loved them to the end.” ESV
If you think that the common translation is correct you have a bigger problem in there is a glaring contradiction, unless one properly translaters "protos" as "before" rather than "first" and adding the word "day" to the greek text
All the Scriptres have to be taken into consideration and the Konie Greek original as opposed to traditional translation.