'Month' in the Bible

In the second year of Darius the king [of Persia], on the first day of the sixth month (Aug 29, 520 b.c.), the word of the Lord 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,

on the twenty-fourth day of the sixth month (Sept 21, 520 b.c.) in the second year of Darius the king.

On the twenty-first day of the seventh month (Oct 17, 520 b.c., the second year of Darius king of Persia), the word of the Lord came by the prophet Haggai, saying,

On the twenty-fourth day of the ninth month (Dec 18, 520 b.c.), in the second year of Darius, the word of the Lord came to Haggai the prophet, saying,

‘Do consider from this day forward, from the twenty-fourth day of the ninth month; from the day when the temple of the Lord was founded, consider:

And again the word of the Lord came to Haggai on the twenty-fourth day of the month (Dec 18, 520 b.c.), saying,