The time frames have to be arranged on a time line of events according to what the events are about.
The second formula is directly from one chapter - Revelation 12.
1260 days + the undisclosed war in the second heaven time + the time, times, half time = 2520 days (7 years)
That the events when totaled are 7 years is validated by the Ezekiel 39 breakdown of the verses following the Gog/Magog event.
Gog/Magog - then the 7 years (verse 9) - then Armageddon (verses 17-20) - then Jesus's return (verses 21-29)
Then you have the return and rapture at a specific time, the last second of your formula.
The time given in Revelation 12 is an historical parenthetical.
This is the list of times and events from Revelation 12:
A.
"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."
These 1260 days happened in the first century. They cannot happen again.
B.
"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."
This is the same 42 months the 2 witnesses are on the earth, and Israel is not. The redeemed remnant are waiting on the sea of glass.
We know this because in Revelation 4:6, the sea of glass is empty:
"And before the throne there was a sea of glass like unto crystal."
John would be the first to arrive to see the soon coming events. Then in Revelation 15:2-3 we see: Israel, the redeemed remnant from Revelation 12:14 on the sea of glass.
"And I saw as it were a sea of glass mingled with fire: and them that had gotten the victory over the beast, and over his image, and over his mark, and over the number of his name, stand on the sea of glass, having the harps of God. And they sing the song of Moses the servant of God, and the song of the Lamb, saying, Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints."
These people are rejoicing in Revelation 12 and 15 as the redeemed remnant of Israel and the 144k who got the victory, but are waiting for a times, time, and half a time, who return from the sea of glass on white horses. So when they leave on eagle's wings is when they left on white horses.
This second set of 42 months start after the 7th Trumpet has sounded and is the 3rd woe. This is the only period of the beast and FP. There is no "first half" nor "second half" mentioned in Revelation 12.
This 42 months is the same 42 months in Revelation 11, as the 2 witnesses are the only redeemed on the earth. No one on the earth is redeemed, at that point, at least not until they chop their head off, and then they are physically dead until after Armageddon. They are waiting for a body and resurrection. Those on the sea of glass are not waiting for a resurrection, as they return like they left.
Those on the sea of glass are physically moved to the sea of glass on white horses the same as they will physically return at Armageddon.
There is only one time frame in Revelation that relates to the Second Coming, and that is when Satan is in control of the entire earth with his mystery Babylon Kingdom. This is the only time frame of the 2 witnesses.
There is no event nor Judgment from God, other than the plagues caused by the two witnesses, during this time handed over to Satan, the 3rd woe. The 5th and 6th Trumpet, and the first 2 woes cannot happen during Satan's 42 months. That 42 months is calm of events, from God, until the 2 witnesses are killed. During the 3.5 days they physically lay dead, are when the 7 vials are poured out.
Your whole foundation is placed on Daniel 9:27 as being 7 years.
The week in Daniel 9:27 consists of the 7 days of the 7th Trumpet. The 3.5 days the 2 witnesses are dead is the last half of Daniel 9:27. That is the Scriptural formula match. Jesus is declared King, and 3.5 days later the week may split in half. One half prior to Satan's 42 months. One half after. And that half, 3.5 days is the last half of a week split into two sections. The 3rd woe are those 42 months, not half of some imagined set of 7 years.
This erroneous, left behind, 7 year tribulation, scenario is not even found in Scripture, but a wrong interpretation, considering that this scenario contradicts both Matthew 13 and Matthew 25. And no such scenario is found in the entire book of Revelation.
