Scholars from all over the world publish books and other documents about their studies on what they expect or predict the “Great Tribulation” to be and when they believe it will happen.  But as all Christians know, only God knows that, and he’s not telling.  God has provided definite information throughout the bible about what the Great Tribulation will be like, and how long it will last (chapters six through eleven in the book of Revelations).  But he chose to leave out the part on exactly WHEN it will happen.
 
The bible tells us that during the seven years of tribulation, there will be more suffering and destruction than any other period of time (past present and future), as we know it.  And it will be universal, personal, and final!  During these seven years, God will pass judgment on all the nations of the world, beginning with Israel, the “beautiful land.”  It will begin with the “Rapture of the Church”, and end with the judgment of the Gentiles (Matthew 25:3146).

Again, knowing WHEN the time of judgment will happen, no one knows.  As our government likes to say, they provide information to the citizens on a “need to know basis.”  And according to scripture in the bible, God will let us know when we need to know (on his timeframe).