The Disciples of Jesus Christ asked Him “What will be the sign of your coming?”
Jesus told them what to expect from the time of the discourse to the end of the dispensation of grace.
The Apostles understood the signs to be His visible return but did not know the signs for rapture. After He was glorified and returned to heaven Jesus knew when the rapture would happen.
Rapture-specific signs were revealed by the Lord to Apostle John on exile in the Island of Patmos in present-day Turkey.