'First Day' in the Bible

In the second year of Darius the king, in the sixth month, in the first day of the month, the Word of Yahweh came by Haggai, the prophet, to Zerubbabel, the son of Shealtiel, governor of Judah, and to Joshua, the son of Jehozadak, the high priest, saying,

In the seventh month, in the twenty-first day of the month, the Word of Yahweh came by Haggai the prophet, saying,