'First Day' in the Bible

From the first day of the seventh month began they to offer burnt-offerings unto Jehovah: but the foundation of the temple of Jehovah was not yet laid.

For upon the first day of the first month began he to go up from Babylon; and on the first day of the fifth month came he to Jerusalem, according to the good hand of his God upon him.

And the children of the captivity did so. And Ezra the priest, with certain heads of fathers houses , after their fathers houses, and all of them by their names, were set apart; and they 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 married foreign women by the first day of the first month.