The timing of the rapture is determined by our free will faithfulness......The moment we witness to and through the power of the Holy Spirit get the last member of the church saved, the trumpet will sound..... You see, every one of Jesus sheep will hear the gospel and follow HIM.
 
John 10:27 My sheep hear my voice, and I know them, and they follow me:

John 10:28 And I give unto them eternal life; and they shall never perish, neither shall any [man] pluck them out of my hand.

John 10:29 My Father, which gave [them] me, is greater than all; and no [man] is able to pluck [them] out of my Father's hand.

          John 10:30 I and [my] Father are one.

The few number of people accepting Jesus today is a sign of the soon coming, as almost all the church has been saved. This is a certain, definite pre-ordained number,,People that were for-ordained before the foundation before the foundation of the world to be saved... If you are not faithful in witnessing to your neighbor, the rapture is put on hold until GOD finds someone willing to witness to him so that through his own free will he gets saved.

Both free will and predestination are true and are at work here.

Lewis  Brackett