The Great Tribulation can't happen until the world ruler makes a seven year peace treaty with Israel.

(Daniel 9:27 NIV) He will confirm a covenant with many for one 'seven.' In the middle of the 'seven' he will put an end to sacrifice and offering. And on a wing of the temple he will set up an abomination that causes desolation, until the end that is decreed is poured out on him."

I expect the Ezekiel 38 and 39 prophecies to be fulfilled as well. A multinational attack on Israel will be lead by Iran. It will include Turkey. Some say Russia as well. Israel will burn the weapons as fuel for 7 years. That has to happen before the pre-trib Rapture of the church.