Why do you go against the Scriptures when it's not that difficult to read?
For the sake of others I'll cover it from the Old Testament, not for you:
Ex 12:5-18
5 Your lamb shall be without blemish, a male of the first year: ye shall take it out from the sheep, or from the goats:
6 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.
14th of Nissan, at evening, the passover lamb was to be sacrificed. That is when Jesus was crucified, on the 14th of Nissan per this requirement, as Apostle Paul said in 1 Corinthians 5:7 that Jesus our passover is sacrificed for us.
7 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.
8 And they shall eat the flesh in that night, roast with fire, and unleavened bread; and with bitter herbs they shall eat it.
9 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.
10 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.
11 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.
12 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.
13 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.
At sunset on the 14th Nissan began the first day of the passover, and they were to eat the passover that night. This is now the 15th of Nissan.
14 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.
15 Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.
16 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.
17 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.
18 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.
KJV
The feast was to begin "at even", meaning at evening, after sunset on the 14th Nissan. That means the preparation and sacrifice was on the 14th Nissan at evening, and then at sunset began the 15th and thus the 1st day of the feast, which was to be a 'high day', a sabbath (but not the regular weekly sabbath).