The disciples came to him privately. "Tell us," they said, "when will this happen, and what will be the sign of your coming and of the end of the age?" (Matthew 24:3)
Two questions in one! First - when will Jerusalem's temple be destroyed - as prophesied by Jesus (v. 1,2); and secondly what will precede Christ's final return? So Jesus replies with two answers in one!
Jesus here takes the impending destruction of the temple (which happened in 70 AD under the Romans) as an immediate and local forerunner of the greater crisis - His final return at the close of history (v.30,31). Thus the local disruptions preceding the temple's destruction would be repeated in the run-up to the end of the world - though on a larger scale. The one would be the 'rehearsal' of the other.
Fraudulent 'Christ's' (v. 4) have peppered history - but similar figures also emerged in the period between Jesus' ascension and the fall of Jerusalem. It was the same with wars and disasters (v. 6-8). The Jewish historian Josephus catalogued local conflicts such as between Arabians and Parthians; also famines and plagues in Babylonia, Crete, Rome, Laodicea and Macedonia. And the 'persecutions' of verse 9 could equally be applied to that period, for the persecuting emperor Nero died only two years before the fall of Jerusalem. And the prophecy that the Gospel must first be preached to all nations was fulfilled in miniature at Pentecost, by participants from 'every nation under heaven' (Acts 2:5).
Here, then, was the warning; first, to get ready for the immediate crisis - but this, in itself, would simply be the rehearsal of the march of history that would lead up to the end of the world. Today that's OUR cue....