this is not how Passover is counted. The lambs were slaughtered at the end of the 14th, not the beginning. thus the lamb was slaughtered around 3 pm and eaten with the unleavened bread which started at sundown on the 15th. They were eaten together. The passover was not a sandwich, nor was it the first meal of the day. Sandwiches were not even invented until a couple hundred years ago!

Also the commandment for unleavened bread is not to not eat yeast, but to not eat anything with leaven. English translations muddy this fact. You are not to eat anything with leaven or a sourdough type starter is not to be found in your homes either.

John says—-after the ceremonial “lamb sandwich” was consumed, the rest of the 14th was spent in preparation for the coming feast because no work could be done after sundown. ——

Please , it was not a lamb sandwich! You are detracting from this most holy meal and taking the true meaning away from it. You say the rest of the 14th, the end of the 14th was spend on slaughtering the lamb and roasting it. Preparations for the “Sabbath were done before then. But cooking of matzah or anything else needed for the 15th could be done on the 15th.

JOhn said—-He fulfilled the prophecy, being selected on the 10th day of the month. It was Palm Sunday.————–

it was actually a Shabbat, the 10th of Aviv that year was a Shabbat, it was not a Sunday.

He actually was crusified the morning of the 14th and died at 3pm and was buried, ( still the 14th) before sundown. So was in the grave wednesday night to thursday night, day 1, thursday night to friday night, day 2, and friday night to sat night, right before sundown, day 3 and he arose before sundown on the Sabbath still because he is Lord of the Sabbath, but was not discovered until the dawning of the first of the week, which is saturday night after sundown, because you were to stay inside your homes on Shabbat.