I think most Christians have made a fundamental error in equating the tribulation with the 70th week in Daniel and therefore with it being 7 years long.
I cannot find any verse that says the tribulation is 7 years long. The famine is 7 years long, the witnesses have a ministry for 42 months, which is 3 1/2 years. But, Jacob's trouble which could be considered a type of the "tribulation" is depicted by the ten days from the Feast of Trumpets to the Day of Atonement. So that would indicate 10 years.
To me, the 69th week ended with Jesus being crucified, so it makes sense that the 70th week would begin either with Nisan 1, or Passover, or Nisan 17 (the day of resurrection). So when I say "welcome to the tribulation" I am not referring to the 70th week. I don't believe that week starts until after the rapture. The 70th week is when the Lord turns his attention to Israel because the "times of the Gentiles" is over and it ends with the rapture of the church.