The record of a great multitude standing before God's throne and before the Lamb in Revelation 7:9-17, given immediately after the sixth seal, implies that the rapture of the believers should begin before the opening of the sixth seal. This record presents a picture in a general way of all God's people raptured to heaven from the time before the sixth seal to their enjoyment in eternity. This is a vision inserted between the sixth and seventh seals.
The first four trumpets, consisting of the four aspects of the intensified supernatural calamities on the earth and on the heavens (Rev. 8:7-12), will take place at the very beginning of the three and a half years, as a direct continuation of the sixth seal, the initiation of the supernatural calamities, and will probably all be trumpeted on the same day.
The last three trumpets will be the three woes (Rev. 8:13). The calamities of the first four trumpets will touch only the earth and heaven, whereas the woes of the last three trumpets will hurt man's body.
The fifth trumpet, as the first woe, will be brought in by Satan, who as a star will fall out of heaven to the earth at the beginning of the three and a half years and will collaborate with Antichrist, the angel of the abyss, to torment men by the demon-possessed locusts for five months (Rev. 9:1-11; 12:9, 11-12).
The sixth trumpet, as the second woe, will be the plague of the four angels who are loosed from their bonds at the great river Euphrates to kill the third part of men for thirteen months, one day, and one hour, by two hundred million horsemen (Rev. 9:12-21). These thirteen months plus the five months of the fifth trumpet will be one and a half years of the three and a half years of the great tribulation. The locusts of the fifth trumpet only torment men for five months, whereas the two hundred million horsemen kill the third part of men. This means that the woe of the sixth trumpet is more severe than that of the fifth.