You evidently, it would seem, do not believe the same evidence in the same way I do.
John 12:1-12.
Mark 14:12.
Mark 14:17.
Mark 15:42-43.
Luke 24:20-21.
Jewish days of the week begin at sunset.
Roman named days of the week begin at midnight.
Unleavened bread the 7 days sunset beginning the 14th. Ending with sunset the 21st. 14-20.
7 days of unleavened bread are the command.
The Feast of unleavened bread 15-21.
Only 6 actual days of unleavened bread are commanded, per Deuteronomy 16:8.
We may not believe the evidence in the same way.
I believe that the Jewish day begins at sundown (not sunset, but technically the end of sundown).
So, per my statement, I believe that the Jewish Sabbath begins at sundown prior to the Sabbath night.
I believe (I know you disagree, which is fine) that our days of the week (Julian Calendar) begin a moment after midnight (think "military time").
So I believe that Friday at the moment the sun has gone down begins the Jewish Sabbath.
I get you disagree but think about the reason the Jews start the day of the week at sundown:
The earth was formless and void, and darkness was over the surface of the deep, and the Spirit of God was moving over the surface of the waters.Then God said, “Let there be light”; and there was light.God saw that the light was good; and God separated the light from the darkness.God called the light day, and the darkness He called night. And there was evening and there was morning, one day. (Genesis 1:2-5)
What was one day? Night and Day. Dark and light. One day.
If you are beginning your dates at sunrise then they will always be off.
Regarding counting, this is also why a partial night-day counts as a day. Say it is Monday afternoon. From Monday afternoon to 11 pm Tuesday is 2 days (not by our counting, but by Jewish reckoning of days).
If a Jew were informed at twilight a loved one had died, for example, that partial day counts as the first full day of shiva.
We see this with Esther's fast as well (Esther 4).
Esther fasted for 3 days and 3 nights. But by our counting she fasted 1 full day, an evening and a morning.
My point is you cannot simply impose our days and reckoning onto the ancient Hebrews.