Will there be prophetic signs leading up to the Second Coming when Christ returns to the Mount of Olives?
Yes. When Christ returns to the Mount of Olives in fulfillment of the Second Coming, prophetic events will lead up to it, so there will be no doubt as to when He comes there. By contrast, the resurrection and changing of the body occurs without a prophetic sign indicating its day or year.
Les teaches that the Second Coming, when Christ actually returns to the Mount of Olives, will have prophetic events leading up to it, so there will be no doubt as to when He will come at the Mount of Olives. He contrasts that with the event described in verse 52: it takes place in a moment, in the twinkling of an eye, at the last trump, when the dead are raised incorruptible. That event has no prophetic sign and nothing to indicate the day or year it will happen. Verse 53 adds that the corruptible must put on incorruption and the mortal must put on immortality; flesh and blood gives way to flesh and bone activated by the Spirit.