'First Day' in the Bible

On the first day of Unleavened Bread, when they sacrifice the Passover lamb, His disciples asked Him, “Where do You want us to go and prepare the Passover so You may eat it?”

Very early in the morning, on the first day of the week, they went to the tomb at sunrise.

[Early on the first day of the week, after He had risen, He appeared first to Mary Magdalene, out of whom He had driven seven demons.