Other posts have determined that it occurs after the Great Tribulation.
Daniel 12:11-12King James Version (KJV)
11 And from the time that the daily sacrifice shall be taken away, and the abomination that maketh desolate set up, there shall be a thousand two hundred and ninety days. 12 Blessed is he that waiteth, and cometh to the thousand three hundred and five and thirty days.
Revelation 6:9-11King James Version (KJV)
9 And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held: 10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth? 11 And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.
Revelation 7:14-17King James Version (KJV)
14 And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb. 15 Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them. 16 They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat. 17 For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of waters: and God shall wipe away all tears from their eyes.
Matthew 24:21-22King James Version (KJV)
21 For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be. 22 And except those days should be shortened, there should no flesh be saved: but for the elect’s sake those days shall be shortened.
The signs signaling the end of the Great Tribulation and 2nd coming:
Matthew 24:29-30King James Version (KJV)
29 Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken: 30 And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.
Joel 2:31King James Version (KJV)
31 The sun shall be turned into darkness, and the moon into blood, before the great and terrible day of the Lord come.
Acts 2:20King James Version (KJV)
20 The sun shall be turned into darkness, and the moon into blood, before the great and notable day of the Lord come:
Revelation 6:12King James Version (KJV)
12 And I beheld when he had opened the sixth seal, and, lo, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood;
The coming will be pronounced:
1 Thessalonians 4:16-17King James Version (KJV)
16 For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: 17 Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
The dead rise first and then after that the alive meet in the clouds.
It will be like a thief in the night:
2 Peter 3:10King James Version (KJV)
10 But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.
Not even Jesus knows the hour of His coming:
Matthew 24:36King James Version (KJV)
36 But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only.
With all the above being said, there seems to be many things that people are trying to use to predict the date of the “Rapture.” A blood moon happened Sept 27, 2015.
This year a number of doomsdayers are predicting Sept 23, 2017 as the “Rapture” based on a major solar eclipse on Aug 21 – issue is that it travels in a southeasterly diagonal from Washington state to Florida.
The latest chain of events as of this writing is North Korea threatening a nuclear missile strike on Guam mid August.
Certain other things have to occur first:
Revelation 14:6-7King James Version (KJV)
6 And I saw another angel fly in the midst of heaven, having the everlasting gospel to preach unto them that dwell on the earth, and to every nation, and kindred, and tongue, and people, 7 Saying with a loud voice, Fear God, and give glory to him; for the hour of his judgment is come: and worship him that made heaven, and earth, and the sea, and the fountains of waters.
The gospel has to be preached. Rev 14:6 would be evident in the number of non-mainstream religions that have emerged in the 19th and 20th centuries (Mormonism, 7th Day Adventists, Jehovah’s Witnesses, Iglesia Ni Cristo, Armstrongism, Members of Church of God International, International Church of Christ, Biblical Unitarianism, Christian Churches of God, etc). The question is which preach the true gospel.
Rev 14:7 would be exposure of religious leaders of various “Christian-professing” sects. Remember from previous studies that an hour in heaven is 41 years and 8 months. In the late 1970s, televangelists have been exposed for vices and misdeeds. Catholic priests have been exposed (and their leadership is taking action). It has extended to non-mainstream religions in the past 10 years or so.
Worldwide wars and rumors of wars (Matt 24:6-8) have been happening since 1914. The final war and famine will kill 1/4 of the population of the earth (Rev 6:8) before the Great Tribulation is finished.
The calling of the 144,000 in Rev 7:2-8 has to be complete.
At the time of the 2nd coming is the fall of Babylon (Rev 14:8).
During the millennium the gospel is preached (Rev 14:12-20) but not by religious leaders, rather the 144,000.