The biblical day went from sundown to sundown, 6pm - 6pm.
Leviticus 23:32 It shall be unto you a sabbath of rest, and ye shall afflict your souls: in the ninth day of the month at even, from even unto even, shall ye celebrate your sabbath.
Genesis 1
5 And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
13 And the evening and the morning were the third day.
The bodies could not remain on the cross but had to be taken down by evening, 6pm, because that was the beginning of the high day sabbath.
John
31 The Jews therefore, because it was the preparation, that the bodies should not remain upon the cross on the sabbath day, (for that sabbath day was an high day,) besought Pilate that their legs might be broken, and that they might be taken away.
32 Then came the soldiers, and brake the legs of the first, and of the other which was crucified with him.