The seven seals, seven trumpets, and seven bowls (and Armageddon) must occur consecutively.
The seals (chapters 6-8) are followed by the trumpet judgments (chapters 9-11), which are followed by the bowl judgments (chapters 15-16), which are followed by the Battle of Armageddon (chapter 19), in successive chapter order.
The seventh seal, which initiates the Day of the Lord, has no judgment associated with it except for the seven trumpet judgments that occur at it's breaking. When the seventh seal is broken, the large scroll can be opened.
The seventh trumpet (Rev 11:15) likewise has no judgment associate with it. The blowing of the seventh trumpet is followed by the opening of the temple in Heaven (Rev 11:19). Out of the temple, the seven angels come forth with the seven bowl judgments (Rev 15:6-8), a time referred to as "the last, because in them the wrath of God is finished" (Rev 15:1).
The contents of the seals, trumpets, and bowls are different and distinct, and permit no overlap of events without doing injustice to the clear differences given us in Scripture concerning each of them.
For example, at the fifth trumpet judgment, the 144,000 are protected by the seal on their foreheads (Rev 9:4). This sealing does not occur until after the sixth seal has been opened (Rev 7:3). This makes it obvious that the fifth trumpet must occur after the sixth seal has been opened.
The four living creatures administer the first four seals (Rev 6:1-8), whereas angels administer the trumpets (Rev 8:6) and the bowls (Rev 15:8).
Armageddon is the last chronological event of this discussion.
