31:1 Now when all this was finished, all Israel that were present went out to the cities of Judah, and brake the images in pieces, and cut down the groves, and threw down the high places and the altars out of all Judah and Benjamin, in Ephraim also and Manasseh, until they had utterly destroyed them all. Then all the children of Israel returned, every man to his possession, into their own cities.
31:7 In the third month they began to lay the foundation of the heaps, and finished them in the seventh month.
(See Scofield "Judges 3:7") .
third month i.e. June.
seventh month i.e. October.