Many are asking when the Great Tribulation will start. We don’t need to guess. Jesus laid it all out in Mathew 24:15-21. 

“Therefore when you see the ‘abomination of desolation,’ spoken of by Daniel the prophet (Dan 9:27), standing in the holy place” (whoever reads, let him understand), “then let those who are in Judea flee to the mountains. Let him who is on the housetop not go down to take anything out of his house. And let him who is in the field not go back to get his clothes.But woe to those who are pregnant and to those who are nursing babies in those days! And pray that your flight may not be in winter or on the Sabbath. For then there will be great tribulation, such as has not been since the beginning of the world until this time, no, nor ever shall be.”

The abomination of desolation is when the Anti-Christ defiles the Temple at the midpoint of the last seven years before Christ comes.

“Let no one deceive you by any means; for that Day will not come unless the falling away comes first, and the man of sin is revealed, the son of perdition, who opposes and exalts himself above all that is called God or that is worshiped, so that he sits as God in the Temple of God, showing himself that he is God. Do you not remember that when I was still with you I told you these things?” 2 Thess 2:3-5