Here it is stated that after the 1260 days, a beast will arise from the abyss and destroy the two witnesses.
Doesn't say that the beast will arise from the abyss after the 1,260 days it says the beast that ascends from the abyss is the one who will kill them when they have finished their witnessing, which is of course after the 1,260 days. But again, that does not mean the beast comes out of the abyss at that time, it already came out at the beginning of the 1,260 days corresponding to the death stroke being healed.
[ 8 The wild beast that you saw was, but is not, and yet is about to ascend out of the abyss, and it is to go off into destruction. And when they see how the wild beast was, but is not, and yet will be present, those who dwell on the earth will wonder admiringly, but their names have not been written upon the scroll of life from the founding of the world.]
[3 And I saw one of its heads as though slaughtered to death, but its death-stroke got healed, and all the earth followed the wild beast with admiration. 8 And all those who dwell on the earth will worship it; the name of not one of them stands written in the scroll of life of the Lamb who was slaughtered, from the founding of the world.]
9:13-21 Trumpet blast six (2nd Woe)
11:3-6 Start of public ministry of two witnesses11:14-18 Trumpet blast seven (3rd Woe)
11:2 Earthly temple courtyard trampled by nations
11:7-13 Death of the two witnesses
Seals 2-4 = death-stroke on beast 7th head/king
The healing of the death-stroke is when it becomes the 8th king for 42-months.
The 42-month period is the GT, it is the hour of judgment from God. The test is do you refuse the 'mark' in support of God's kingdom or do you take the 'mark' in support of Satan's false kingdom. Those that take the 'mark' (goats) will undergo everlasting cut off after the 42-months when Jesus comes at Armageddon. Those that refuse the 'mark' (sheep) will be who make up the great crowd and inherit God's kingdom. (Some from among those will rule with Jesus for the 1,000 years.) Revelation 14:9-12;15:2;7:9,10,13-17;20:4;19:20,21
The 42-months that the 8th king rules corresponds to the holy city being trampled and the two-witnesses.
That time takes place during the 6th trumpet/2nd woe.