Christ will come to the air probably before the trumpeting of the seventh trumpet (Rev. 10:7a), for the purpose of taking full possession of the earth (Rev. 10:1-7). He will come down to the air and get everything ready so that He can come to the earth directly to take full possession of it.
The city of Jerusalem will be trampled by Antichrist for forty-two months, that is, a thousand two hundred sixty days, during the great tribulation, and the two witnesses of the Lord will prophesy during that time and will be killed by Antichrist and resurrected to be raptured into Christ's parousia (presence) in the air (Rev. 11:1-12).
There will be a great earthquake, the tenth part of the city of Jerusalem will fall because of the earthquake, and seven thousand will be killed in the earthquake (Rev. 11:13).
Now we need to see the contents of the seventh trumpet, which will probably be trumpeted on the last day of the three and a half years.
The first item on the positive side is the finishing of God's mystery. This is declared in Revelation 10:7. Daniel 9:24 says that the seventy weeks were apportioned out to seal up vision and prophet. To seal up vision and prophet is to finish the mystery of God. In the church age, the age of grace, everything concerning Christ and the church is a mystery (Eph. 5:32), but when the seventh trumpet is sounded, the age of mystery will be over.
The seventh trumpet includes the rapture of the majority of the believers—the resurrected ones and the remaining ones—into Christ's parousia (presence) in the air (Rev. 20:4-6; 14:14-16; 1 Cor. 15:52; 1 Thes. 4:16-17).