seventh month
i.e. October; Nehemiah 8:2; Nehemiah 8:14.

for since the days of Jeshua
It is not meant that there had not been some formal observance of the feast of tabernacles (cf) 2 Chronicles 8:13; Ezekiel 3:4; Ezekiel 3:4 but that the people had not dwelt in booths since Joshua's days.