The book states ‘no one knows when’ several times; even in Revelations, the book literally about end times.

And there are many times in modern human history that people were sure it had kicked off. But it didn’t and things just got better again. It’s like our thing to almost wipe ourselves out but miserably kick on for another day.

We only just appeared here anyway so we’ll likely disappear just as recently as well and some other living thing will have its turn, and so on, and so on, until the sun takes out the atmosphere and then the planet. And fin.