The scripture verses in the book of Revelation present a timeline for when the rapture takes place during the tribulation. There are sign posts/events along the way within the chapters of the book of Revelation that mark when the rapture takes place. In regards to this timeline, it is important to always keep in mind that the three woes are linked to the last three Trumpets.
Revelation 8:13 KJVS
 And I beheld, and heard an angel flying through the midst of heaven, saying with a loud voice, Woe, woe, woe, to the inhabiters of the earth by reason of the other voices of the trumpet of the three angels, which are yet to sound!
The above verse establishes a linear chronology throughout the 8th-12th chapters of Revelation based on when these three woes transpire within the narrative. We know for a fact that the two witnesses give their testimony during the first 3 1/2 years of what is commonly called the tribulation, because of what is written in the following verses.
Revelation 11:3,7-13 KJVS
 And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth.  And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them.  And their dead bodies shall lie in the street of the great city, which spiritually is called Sodom and Egypt, where also our Lord was crucified.  And they of the people and kindreds and tongues and nations shall see their dead bodies three days and an half, and shall not suffer their dead bodies to be put in graves.  And they that dwell upon the earth shall rejoice over them, and make merry, and shall send gifts one to another; because these two prophets tormented them that dwelt on the earth.  And after three days and an half the Spirit of life from God entered into them, and they stood upon their feet; and great fear fell upon them which saw them.  And they heard a great voice from heaven saying unto them, Come up hither. And they ascended up to heaven in a cloud; and their enemies beheld them.  And the same hour was there a great earthquake, and the tenth part of the city fell, and in the earthquake were slain of men seven thousand: and the remnant were affrighted, and gave glory to the God of heaven.
These verses give us some very important details. The ministry of the two witnesses takes place before the first and second woe. The beast that ascends out of the bottomless pit, first woe (5th trumpet), kills the two witnesses. The second woe takes place when the great earthquake occurs in Jerusalem following the death and resurrection of the two witnesses. The seventh trumpet and third woe takes place shortly after the second woe.
Revelation 11:14-15 KJVS
 The second woe is past; and , behold, the third woe cometh quickly.  And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
Apostle John writes a verse in the tenth chapter of the book of Revelation that is in harmony with Rev 11:15, and with a revelation given to Apostle Paul.
Revelation 10:7 ESV
 but that in the days of the trumpet call to be sounded by the seventh angel, the mystery of God would be fulfilled, just as he announced to his servants the prophets.
The mystery of God is Christ in you the hope of glory, Col 1:27. Apostle Paul was given a dispensation by God to preach the revelation of the mystery of God, which fulfilled the word of God, Col 1:25. A short word study on the word mystery as it appears in the New Testament is helpful if one is unfamiliar with this mystery. Paul writes of this mystery in the often quoted verses in the 15th chapter of 1 Corinthians.
1 Corinthians 15:51-52 KJVS
 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,  In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
At the seventh trumpet the members of the body will receive their glorified bodies and rule and reign with Jesus Christ for a thousand years, Rev 20:6. Which will be God’s glory in the kingdom to come, 1 Th 2:12. A interesting aspect of the mystery of God, mystery of Christ, is that God has to make known to a individual, what is the riches of the glory surrounding this mystery. So many bible experts do not understand this mystery because it is not given for them to know.
Colossians 1:27 KJVS
 To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory:
The last trump/trumpet that sounds, is the seventh trumpet and that is when the mystery of God is finished.
Revelation 11:15 KJVS
 And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
Many try to take the 12th chapter of Revelation and place it at the beginning of the tribulation, Rev 4:1, or at the sixth seal in support of a pre tribulation rapture theory. But again, the three woe that are linked to the last three Trumpets, makes that impossible. If in fact one views the man child as the body of Christ, and the man child caught up to the throne of God, Rev 12:5, as the rapture. The third woe is when Satan is cast down to earth, Rev 12:12, following the man child being caught up to the throne of God, Rev 12:5. It is very easy to loose sight of the fact that the three woes are associated with the last three Trumpets, Rev 8:13, while reading through the scripture verse of the 8th-12th chapters. Many also view the woman in Revelation 12 as Mary the mother of Jesus. But again, the three woes makes that also impossible since the three woes are linked to the last three trumpets. There are two seed of the woman mentioned in the 12th chapter of Revelation. The man child who is resurrected at the seventh trumpet, verse 5, and the remnant of the woman’s seed, verse 17, who Satan makes war against during the last 3 1/2 years of the tribulation.
Revelation 12:17 KJVS
 And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.
So you have two seed of the woman, one group resurrected/changed at the middle of the tribulation and another group that are on the earth during the final half of the tribulation. The woman flys into the wilderness for three and a half years. The wilderness is a place where one is tested and tried by God. http://www.justifiedfreely.com/?p=724
Revelation 12:14 KJVS
 And to the woman were given two wings of a great eagle, that she might fly into the wilderness, into her place, where she is nourished for a time, and times, and half a time, from the face of the serpent.
Rev 12:17 may in fact account for verses in other parts of the Bible that point to a post tribulation resurrection. Possibly the resurrection of the just and unjust our Lord mentions in the latter half of the 25th chapter of Matthew. If I were to speculate upon the difference between those in the man child and those mentioned in Rev 12:17, I would say the baptism of the Holy Ghost.
Matthew 3:11-12 KJVS
 I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire:  Whose fan is in his hand, and he will throughly purge his floor, and gather his wheat into the garner; but he will burn up the chaff with unquenchable fire.
This baptism is a powerful and memorable experience, and in my case accompanied by speaking in tongues. When in fact might the rapture take place in regards to the Gregorian calendar?
Luke 3:1-3 KJVS
 Now in the fifteenth year of the reign of Tiberius Caesar, Pontius Pilate being governor of Judaea, and Herod being tetrarch of Galilee, and his brother Philip tetrarch of Ituraea and of the region of Trachonitis, and Lysanias the tetrarch of Abilene,  Annas and Caiaphas being the high priests, the word of God came unto John the son of Zacharias in the wilderness.  And he came into all the country about Jordan, preaching the baptism of repentance for the remission of sins;
Tiberius Caesar’s reign started in 14 AD, 15 years later the ministries of John the Baptist and our Lord started. The Lord’s ministry lasted for 3 1/2. Which places the crucifixion of our Lord in and around AD 33. There are two thousand year prophetic days, 2 Pe 3:8, before our Lord’s return at the start of the seventh day, which would place the start of the thousand year kingdom of God around AD 2033. Since the rapture, gathering of the Saints unto the Lord, is 3 1/2 years before 2033, Rev 10:7, that gives rough target date of 2029 for the rapture, if not sooner, Mark 13:20. I for one, hope sooner.