I thought your view was actually almost accurate. But it's not.
[Num 9:2-3 LSB] 2 "Now, let the sons of Israel observe the Passover at its appointed time. 3 "On the fourteenth day of this month, at twilight, you shall observe it at its appointed time; you shall observe it according to all its statutes and according to all its judgments."
[2Ch 35:1 LSB] 1 Then Josiah celebrated the Passover to Yahweh in Jerusalem, and they slaughtered the Passover [animals] on the fourteenth [day] of the first month.
[Ezr 6:19 LSB] 19 And the exiles celebrated the Passover on the fourteenth of the first month.
Passover is always stated to be on the 14th of Nisan. ALWAYS. Otherwise God Himself is made out to be a liar. And Messiah Jesus would have broken the Law of Moses. Both are obviously not the case.
In addition, it seems people do not have a proper understanding of what the Passover truly means. The word is used without much consideration and accuracy. The Passover as defined by God is on the 14th. It is the sacrifice of the lamb. It is not the meal. It is not the killing of the firstborn. It is not the placing of the blood on the door posts. Yes, those are elements associated with the Passover. But the Passover is the act of SACRIFICE. The substitutionary death of the innocent for the guilty. That is why Passover must be on the 14th. That is the date that Messiah Jesus was sacrificed; His substitutionary death for those that trust in Him.
The act of placing the blood on the door posts is a sign that the sacrifice was complete and trust was placed in it. The meal is a sign that the sacrifice was done according to the instructions of God. The angel of death passing by is the consequence that the sacrifice was acceptable and that the resulting actions were done according to God's instructions. But the Passover is the act of killing the lamb on the 14th of Nisan.
Except you forgot this:
"For I will pass through the land of Egypt this night, and will smite all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the Lord."
"And the blood shall be to you for a token upon the houses where ye are: and
when I see the blood, I will pass over you, and the plague shall not be upon you to destroy you, when I smite the land of Egypt."
The pass over happened after 6pm on the 15th, because the 15 started at 6pm.
You are still trying to fit everything in from 6pm on the 14th to 9am in the morning.
Your translation may back up your assertion, but it is a horrible interpretation. Why is killing the Passover Lamb considered a celebration? Yes it bacame a time of celebration, but you have to do the work to have a feast. The day of the Passover was a day of rest. You can celebrate as rest, but you cannot have the rest until the work is done. The 14th is the day of preparation, not the 13th nor the 15th.
"In the first month, on the fourteenth day of the month at even, ye shall eat unleavened bread, until the one and twentieth day of the month at even."
That means they started this special diet after they prepared all day for it. So in Ezra 6:19 they kept the Passover, or they prepared for the Passover by doing the sacrifice in the temple.
It would be wrong to say they just hung out in the Temple on the 15th. The Temple was not for rest. The Temple was for the preparation or in your translation celebration=killing the lambs as sacrifices. Of course the killing was keeping the Passover. Why would you equate celebrate with killing, though? Do you think they killed the sacrifices on the 13th to celebrate on the 14th?
The original command was to start on the 10th and be done on the 14th, not done before the 14th started.
"In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house. And ye shall keep it up until the fourteenth day of the same month: and the whole assembly of the congregation of Israel shall kill it in the evening."
But they left on the 15th not the 14th. Why would they put the blood and kill the Lamb to eat over 30 hours before leaving? The preparation was done all day the 14th and finished up in the evening that started the 15th. That is why it is the day of preparation. That is why keeping the Passover is considered preparation and not celebration. They started the biggest feast of their lives, and did so picnic style so they could leave at any moment even in the darkness of night.
The 15th was the celebration and day of memorial because that is when their lives were spared.
"And they shall take of the blood, and strike it on the two side posts and on the upper door post of the houses, wherein they shall eat it. And they shall eat the flesh in that night, roast with fire, and unleavened bread; and with bitter herbs they shall eat it. Eat not of it raw, nor sodden at all with water, but roast with fire; his head with his legs, and with the purtenance thereof. And ye shall let nothing of it remain until the morning; and that which remaineth of it until the morning ye shall burn with fire. And
thus shall ye eat it; with your loins girded, your shoes on your feet, and your staff in your hand; and ye shall eat it in haste: it is the Lord's passover."
Because while they were eating, the pass over was happening and the firstborn of those not prepared were dying. When it did actually happen, that is when they left Egypt, and Scripture states they left on the 15th.
"And this day shall be unto you for a memorial; and ye shall keep it a feast to the Lord throughout your generations; ye shall keep it a feast by an ordinance for ever."
Can you convince every Jew currently alive on earth, they have the wrong day as their Passover? They should be preparing on the 13th and resting on the 14th? That day is one day they still keep as an ordinance forever, even if they fail to see the spiritual significance. Then God lengthened the feast for 7days. The 15th was the first day up until the 21st. 7 full days. No work on the 15th. No work on the 21st.
"And in the first day there shall be an holy convocation, and in the seventh day there shall be an holy convocation to you;
no manner of work shall be done in them, save that which every man must eat, that only may be done of you. And ye shall observe the feast of unleavened bread; for in this selfsame day have I brought your armies out of the land of Egypt: therefore shall ye observe this day in your generations by an ordinance for ever.
In the first month, on the fourteenth day of the month at even, ye shall eat unleavened bread, until the one and twentieth day of the month at even."
Once again, that does not mean to start on the 13th and stop on the 20th, but the whole day of the 21st until the next evening. From the 14th to the 21st is 8 whole days. From the 15th to the 21st including the 21st is 7 whole days. The day of preparation, the 14th, was for the whole 7 days of unleavened bread that would follow.