The 70th week is in Revelation 12. The first half is the 1260 days in Revelation 12:6. The second half, after the war in heaven and Satan cast down to earth, is in Revelation 12:14.
The confirmation that those two verses in Chapter 12 added together are the seven years - is in the status of
the crowns on the heads. And
no crowns on the horns. (heads in blue, horns in red)
12:3 And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and
seven crowns upon his heads.
The crowns on the heads is because king 7 will have come to power as the 7 years are about to begin.... completing the prophecy of the 7 kings in Revelation 17.
The crowns are gone from the heads in Revelation 13, because king 7 will have been killed, ending the prophecy of the 7 kings. That chapter has 42 months left.
13:1 And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads
(no crowns) and ten horns, and upon his horns ten crowns, and upon his heads the name of blasphemy.
_______________________________________________________________________
Like proof - the crowns are not on the horns in Revelation 12, because with 7 years in that chapter, the person has not yet become the beast - that the ten kings rule with the beast.
12:3 And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns
(no crowns), and
seven crowns upon his heads.
In Revelation 13, the crowns are on the horns because the person has become the beast.
And the ten kings rule with the beast that last 42 months.
13:1 And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads and ten horns, and
upon his horns ten crowns, and upon his heads the name of blasphemy.
_____________________________________________________________________
So the 7 year 70th week is found in Revelation 12. And the second half, the 42 months is in Revelation 13.
When I first began studying eschatology, 45 years ago, it would really be something that ate at me, the crowns on the heads and horns - and I had to constantly flip back and forth between chapters 12, 13, 17 trying to get it straight in my head what had crowns when, and when no crowns. Writing things down, trying to understand it.
Now, it is like knowing the back of my hand. I can say with 100% confidence the entire 70th week is ahead of us.