I'm sorry....but you are simply incorrect. As I have now said about three or four times on this thread the first day of unleavened was referring to the day of preparation, the 14th [Leviticus 23:5]. It does not say the first day of the Feast which would be the 15th [Leviticus 23:6].
The entire eight day observance was referred to quite often as "The Days of Unleavened" but that does not mean that the Feast was then the first day. It would have been the second day under that terminology. The Day of Preparation was called the first day as you can see also in [Matthew 26:17] KJVKing James Version 26:17 Now the first [day] of the [feast of] unleavened bread the disciples came to Jesus, saying unto him, Where wilt thou that we prepare for thee to eat the passover? The bracketed words do not appear in the original manuscript. They were added by translators!
Here is the Greek [Matthew 26:17]. See if you can find the words "day" and "feast of": th de prwth twn azumwn proshlqon oi maqhtai tw ihsou legonteV autw pou qeleiV etoimaswmen soi fagein to pasca This is where the confusion lies. The KJV translators say First Day of The Feast of Unleavened Bread". The correct translation is "The First of the Unleavened Bread".
This would be along the same manner as someone in our 21st century society saying "The first of the Christmas season". That would not mean the 25th of December.
[Acts 20:6] And we sailed away from Philippi after the days of unleavened bread, and came unto them to Troas in five days; where we abode seven days. When Luke wrote these words he was including Passover Preparation (the 14th).
The intermediate days on the Passover period in-between the High days or weekly Sabbaths were regarded as secular days, thus allowing time for regular activities such as buying, travelling, and working (e.g. preparation of spices).