The dwelling in the sukkahs, according to The Book of Leviticus would be 7 days. This would mean the period from Tishri 14 become 15 at sundown until the sundown ending day 7, Tishri 21, going to the 8th day of Tishri 22, the Last Great Day of Shemini Atzeret. It is stated clearly in Leviticus 23:34-43. "You shall dwell in the sukkot for seven days ... So that your future generations shall know that I had the children of Israel live in sukkot when I brought them out of Egypt." Sukkot must be ready to use as Tishri 15 begins.
But there is a complication since Shemini Atzeret is a no work day, a Yom Tov, so the sukkot should not be dismantled on day 8. It is Jewish custom to add 2 days of Yom Tov for those outside Israel through Shemini Atzeret and Simchat Torah, Tishri 22 and 23. Some people will use the sukkot through days 8 or 8 and 9. In theory, they could stand unused and not dismantled for 1 or 2 days beyond the Scripturally commanded 7 days duration. The Scriptures require living in the sukkot only for a full 7 days. Each sukkah is a temporary dwelling, home, residence for 7 days. The first night should be spent in the sukkah. Meals are meant to be eaten there daily, as well. Might Sukkot, the Season of Tabernacles and the Season of Our Joy, be the Season of The Blessed Hope, between its beginning and conclusion for Israel? We shall see. Come quickly, Lord...
With Love and Shalom,