And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars:  And she being with child cried, travailing in birth, and pained to be delivered.  And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads.  And his tail drew the third part of the stars of heaven, and did cast them to the earth: and the dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born.  And she brought forth a man child, who was to rule all nations with a rod of iron: and her child was caught up unto God, and to his throne.  And the woman fled into the wilderness, where she hath a place prepared of God, that they should feed her there a thousand two hundred and threescore days.
Revelation 11:1-12 tells us that the Two Witnesses will preach for 42 months or 1260 days (v. 2-3). It is clear from Scripture that their time of three and a half years is the first half of the Tribulation. Verse 7 says that they are killed by the "Beast from out of the bottomless pit" (see Rev. 9:1-11; 17:8; 20:1-7). This is Satan (Rev. 9:11; 20:2). Even though the Tribulation is covered from Chapters 6-19, with Chapter 13 being the middle of the seven-year period (Dan. 9:27; Mt. 24:15). Chapter 11 is the first we hear of the Two Witnesses.
Likewise, Chapter 12 actually takes place prior to Chapters 6-19. Clarke suggests that the Woman in Chapter 12 is corporate Israel, that her Child is the corporate Body of Christ, and the Dragon represents the corporate New World Order. He says that prior to the Tribulation, "the Dragon desires to destroy the Church, but that it is caught up to heaven (Jn. 14:1-3; 1 Cor. 15:50-54; 1 Th. 4:16-17; Rev. 4:1; 12:6). Frustrated, the Dragon makes a seven-year peace covenant with the Woman, but half way through it, he seeks to destroy the Woman (Israel - see Rev. 12:6-17). For the remaining 42 months; 1260 days, or a time, times, and a half time (Dan. 12:7; Rev. 12:14), the Woman is protected by God (Rev. 12:7-17)!
Like I said earlier, Clarke's explanation make sense to me. However, like the prophecies literally fulfilled by Jesus at His First Coming were not understood until after they were fulfilled, it is likely that we will be proven to have erred with some of our "educated guesses." God is trying to keep us humble, so to declare our interpretation of future fulfillment of prophecy to be a fact, is foolish.
We do not KNOW when He will return for His Church, but it has to be soon!