'First Day' in the Bible

From the first day of the seventh month began they to offer burnt offerings unto the LORD. But the foundation of the temple of the LORD was not yet laid.

And the children of the captivity did so. And Ezra the priest, with certain chief of the fathers, after the house of their fathers, and all of them by their names, were separated, and sat down in the first day of the tenth month to examine the matter.

And they made an end with all the men that had taken strange wives by the first day of the first month.