After me there will arise in the second week great wickedness, and deceit will spring up. Afterwards will be the first end [the Flood]. Mankind will be saved, but unrighteousness will revive, even though he will make a law for the sinners. Enoch 93:4
The extreme wickedness began in the first week. The Ancient Book of Jubilees states that the Genesis 6 angelic rebellion occurred sometime during the days of Jared, Enoch's father. This would be the time between Jared's birth and Enoch's birth, or between 460-622 AM (3464-3304 BC). During the second week all flesh was corrupted. According to Josephus, Adam had predicted two "ends" or two planetary destructions; one by a flood of water and one by a rain of fire. The result of this corruption was the first "end" or Noah's Flood, which occurred after this week of wickedness.
The Flood occurred in 1656 AM (2269 BC). This was the was the second Jubilee of the third century of the third week of centuries.
God saved mankind by using Noah and his sons, Ham, Shem, and Japheth, to repopulate the earth after the Flood. Noah gave the Seven Noahide Laws (briefly described in Genesis 9) to his sons as a bedrock set of laws for all the nations they would create. But the nations fell again into multiple forms of apostasy.