'First Day' in the Bible

Now in the eleventh year, on the first [day] of the month [after the capture of King Jehoiachin], the word of the Lord came to me, saying,

In the twenty-seventh year [after King Jehoiachin was taken to Babylon], in the first month, on the first of the month, the word of the Lord came to me, saying,

In the eleventh year [after King Jehoiachin was taken captive to Babylon], in the third month, on the first of the month, the word of the Lord came to me, saying,

In the twelfth year [after King Jehoiachin of Judah was taken into exile by the king of Babylon], in the twelfth month, on the first of the month, the word of the Lord came to me, saying,