The way the Jewish people counted days back then was that a day began at sundown one day and ended at sundown. So Thursday sundown began Day 1. This is the day when Jesus was crucified and died, Good Friday.
Day 2 was from sundown on Friday through sundown on Saturday, when He was buried.
Day 3 was from sundown on Saturday through sundown on Sunday, the day he arose from the dead.
I think this would be a GREAT billboard on roads and in church educational buildings at Easter as many (including me for a long time) didn’t understand Jewish writings and this baffled me for decades.
After a trip to Israel, one understands much more!
Day 2: Thursday (5th day of the week) evening at sunset to Friday evening at sunset.
Day 3: Friday (6th day of the week) evening at sunset to Saturday evening at sunset.
Our Lord could have risen at any time after sunset on Saturday (7th day of the week). When the women went to the sepulcher EARLY on the first day of the week, Christ was ALREADY risen. There is no Scriptural necessity for Him to have had to wait until sunrise.