I was taught in the past and understood that the verses saying “no-one knows the day or hour” refer to the rapture. I would think that once the temple is desolate, most people can count 3 years. Where have I gone wrong?
Lots of people think the same way you do, because that’s how most of us were taught. But a careful reading of Matt. 24-25 shows that it’s incorrect. In the first place counting 3 1/2 years from the Temple’s desolation only brings us to the end of the Great Tribulation which is described in Matt. 24:29 with the sun and moon going dark.
The Second coming will take place in Matt. 24:30-31. The first “no one knows” phrase appears in Matt. 24:36-37 in reference to the 2nd coming. The next one comes in Matt. 24:42-44, then there’s another one in Matt. 24:50, and the last one in Matt. 25:13. All of them have to do with events that take place after the Second Coming. What this means is that after the sun and moon go dark at the end of the Great Tribulation, no one will know exactly how much time will pass until the Lord returns.
This is one reason why I believe the Second Coming will take place on the Feast of Trumpets. Even though people were expecting it, the Feast of Trumpets could not begin until there were two independent sightings of the New Moon, which is barely visible, even in a clear sky. Because of that the Feast of Trumpets became known as the feast where “no one knows the day or hour.” I think the Lord was giving us a giant hint about the timing of the Second Coming in Matt. 24-25 and most people didn’t get it.