Just in case you have forgotten, we are still trying to figure how long it will be before the Lord returns. In reality, we have been attempting to answer the three-part question of the disciples concerning the timing of "these things" (the destruction of Herod's Temple), "Christ's Second Coming," and "the end of the age (Matt. 24:3). In doing so, we are looking at the events which must occur prior to His return, in reverse order, to find out exactly where we are today in God's timetable. So far, we know that the Second Coming must be preceded by the seven-year Tribulation; Revelation 19 is preceded by Revelation 6 - 18.
The next step is to discover what must occur prior to the Tribulation. The answer is, Revelation 4:1-2, which says, "After this I looked, and, behold, a door was opened in heaven: and the first voice which I heard was as it were of a trumpet talking with me; which said, Come up hither, and I will shew thee things which must be hereafter. And immediately I was in the spirit: and, behold, a throne was set in heaven, and One sat on the throne."
John, being called to "come up hither" by Jesus, the first voice John heard in his vision (Rev. 1:8), is immediately caught up to heaven. I believe John represents the Church, and Revelation 4:1-2 are a picture of the Rapture, the transition between the Church Age (Rev. 2 - 3), and the Tribulation (Rev. 6 - 18). Other passages which describe the Rapture of the Church are found in John 14:1-6; in 1 Corinthians 15:51-54; and in 1 Thessalonians 4:13-18.
And, what comes before the Rapture of the Church pictured in Revelation 4:1-2? It is obvious from the way John began the two verses with the words "After this." After what? Again the answer is obvious: the Church Age (Rev. 2 - 3). So far, we have the Second Coming, preceded by the Tribulation, preceded by the Rapture, preceded by the Church Age. Since we are presently living during the Church Age, is there anything in the Scriptures which tells us when this age will end with the Rapture? Yes!
Jesus said that we are to be the "salt" of the earth, and the "light" of the world, but when the "salt" loses its ability to prevent corruption, and when the "light" fails to reveal God's glory, they become worthless (Matt. 5:13-16). The Church was given two commands: Love one another (Mt. 5:43-48, 7:12, 22:40; Jn. 17:11, 21-23, etc.), and spread the Gospel (Mt. 28:19-20; Acts 1:8). However, the Church has ceased to be of value to the Lord due to its response to His commands: it is marked by division (Rom. 16:17; 1 Cor. 1:10; 3:3; 11:18; Jam. 2:1-9; 4:1-2, 11; 5:9), and by apostasy (2 Thes. 2:3; 1 Tim. 4:12; 2 Tim. 3:1-7; 4:3-4; 2 Pet. 2:1; Jude 4; Rev. 3:15-16). And while we look forward to the Rapture which could occur at any time, the Lord might see it as the removal of His rebellious children who have brought shame upon the His name.
I am not sure I need to say more, but if I do, Lord willing, I will continue tomorrow.