John Gill Commentary Haggai 1:15

"in the four and twentieth day of the month, in the sixth [month], in the second year of Darius the king." — Haggai 1:15 (ASV)

In the four and twentieth day of the sixth month
Or, "in the four and twentieth of the month, in the sixth"; in that sixth month before mentioned, (Haggai 1:1) . On this day they came and worked; not the sixth from Tisri, for the Jews had two ways of beginning their years, which would have answered to part of February; and, therefore, chose by some interpreters as being a proper time to begin building; but no regard is had to the fitness of the season, but to the order of the Lord; but the sixth month from Nisan, and answers to part of August; for so the months are reckoned in the prophecy of Zechariah, who began to prophecy the same year as Haggai did; see (Zechariah 1:1Zechariah 1:7) (Zechariah 7:1)

this was three and twenty days after the prophecy was delivered out; during which time they might be employed in cutting of stones, and sawing and hewing of wood, as Jarchi suggests, and preparing for work in the temple: in the second year of Darius the king; (See Gill on Haggai 1:1).

Here some begin a new chapter, but wrongly; since, if these words do not belong to the preceding, there would be a contradiction in joining them with the beginning of the next.