How could it be about the second coming? The day the tribulation starts, you know to the day when the second coming will be ... exactly 1260 days ... times 2.
Right???
good point- Here’s an explanation- here is what many teach about this:
[[3. When Jesus was saying “no one knows the day or hour” He was communicating several things. First, at the time He spoke those words no one presently living (Himself included) could determine the exact day or hour of any of these future events. Second, the Day of the LORD would come for most (but not all) people like a thief - hence the repeated command to watch. Third, this statement may have incidentally foreshadowed the timing of the rapture of the Church on a future Feast of Trumpets.]]
http://www.unsealed.org/2017/08/no-one-knows-day-or-hour.html
The context in Matthew does mention His second coming- and at His second coming- He will establish His kingdom- I’m pretty sure the context makes this clear
[[No one knows about that day or hour, not even the angels in heaven, nor the Son, but only the Father. As it was in the days of Noah, so it will be at the coming of the Son of Man“ (Matt. 24:36-37).
Let’s back up a few verses to make sure we have the proper context here. After the Great Tribulation ends (Matt. 24:29) there will be various signs in the heavens. The sun and moon will go dark and the stars will fall from the sky. Then the sign of the Son of Man will appear and all the nations will mourn. After that they’ll see Him coming in the clouds with power and great glory (Matt. 24:30). From both the context and the passage itself it’s clear that the day and hour the Lord was referring to in Matt. 24:36-37 is the 2nd Coming .
A few verses later, the Lord repeated the same thought, again in the context of the 2nd Coming.
“Therefore keep watch, because you do not know on what day your Lord will come. But understand this: If the owner of the house had known at what time of night the thief was coming, he would have kept watch and would not have let his house be broken into. So you also must be ready, because the Son of Man will come at an hour when you do not expect him.” (Matt. 24:42-44)]]
https://www.quickening-spirit.com/rapture-day-hour/