When does the Great Tribulation begin?
The Great Tribulation begins at the midpoint of the tribulation, when the Antichrist moves into the temple and defiles it. That defilement triggers the unprecedented time of suffering Jesus described, worse than anything since the world began or ever will be.
Les explains that Jesus, who knows what He is talking about, says that when the Antichrist moves into the temple and defiles it at the midpoint of the tribulation, then shall be great tribulation. This is not the beginning of the tribulation but its midpoint. Jesus describes it as a time such as was not since the beginning of the world to this time, nor ever shall be. Les notes there have been tremendous calamities in history, such as the Flood—an instantaneous cataclysmic destruction—and the Holocaust in Hitler's Germany, but the Great Tribulation will exceed them all. He also connects this to Israel being back under the law, praying their flight not be on the Sabbath day, and possibly fleeing to the Red Rock City of Petra.