'First Day' in the Bible

From the first day of the seventh month they began to offer burnt offerings to the Lord. However, the Lord's temple was not at that time established.

On the first day of the first month he had determined to make the ascent from Babylon, and on the first day of the fifth month he arrived at Jerusalem, for the good hand of his God was on him.

So the exiles proceeded accordingly. Ezra the priest separated out by name men who were leaders in their family groups. They sat down to consider this matter on the first day of the tenth month,

and on the first day of the first month they finished considering all the men who had married foreign wives.