There are thousands of signs, so we can put the "first generation" back very far or forward very far. It all depends what you mean.

My view is: We can say confidently The Four Horsemen of the Apocalypse (Revelation 6) are already roaming today, because Zechariah 6 and Ezekiel 14 (particularly verse 21) say they have been unleashed before. However, they will obtain a greater final commission that has not been released yet.

The first searches of the OP's quote come up with SDA sites (they think the end time started in 1844). Many of the SDA's made peace with evangelical denominations about 60 years ago, but a few are still cultic just like some in any other denomination. SDA's unique eschatology is not contrary to Q (though it rubs up a bit against the dominionism we occasionally see), but it'd be better if the OP cited the Biblical arguments and priority as the SDA's are excellent at doing.

I like to joke that the SDA's, who have said since 1844 that the government will close all businesses on Sundays by institution of "blue law", have finally had their prophecy fulfilled last year, when the government did close all businesses on Sundays (as well as on the other weekdays).