I believe Jesus said that the days of great tribulation started with the temple was being destroyed, and the Jews being exiled to the nations.
Matthews GT, is lukes days of vengeance, and Jesus said they started back then and would continue until the times of the Gentiles were fulfilled.

Quote:

LK 21 "But when you see Jerusalem surrounded by armies, then recognize that her desolation is near. "Then those who are in Judea must flee to the mountains, and those who are in the midst of the city must leave, and those who are in the country must not enter the city; because these are days of vengeance, so that all things which are written will be fulfilled. "Woe to those who are pregnant and to those who are nursing babies in those days; for there will be great distress upon the land and wrath to this people; and they will fall by the edge of the sword, and will be led captive into all the nations; and Jerusalem will be trampled under foot by the Gentiles until the times of the Gentiles are fulfilled.

Quote:

MATT 24 "Therefore when you see the ABOMINATION OF DESOLATION which was spoken of through Daniel the prophet, standing in the holy place (let the reader understand), then those who are in Judea must flee to the mountains. "Whoever is on the housetop must not go down to get the things out that are in his house. "Whoever is in the field must not turn back to get his cloak. "But woe to those who are pregnant and to those who are nursing babies in those days! "But pray that your flight will not be in the winter, or on a Sabbath. "For then there will be a great tribulation, such as has not occurred since the beginning of the world until now, nor ever will. "Unless those days had been cut short, no life would have been saved; but for the sake of the elect those days will be cut short

The GT is from then AD 70 -till he comes, which is why you cant count the number that come out of it in Rev 7.
Its been painful for the Jew in Exile and the Church ever since.