While he was sitting upon the Mount of Olives, the disciples approached him privately, saying: "Tell us, When will these things be, and what will be the sign of your presence and of the conclusion of the system of things?" - Matthew 24:3
And this good news of the kingdom will be preached in all the inhabited earth for a witness to all the nations; and then the end will come.
"Therefore, when YOU catch sight of the disgusting thing that causes desolation, as spoken of through Daniel the prophet, standing in a holy place, (let the reader use discernment,) ... for then there will be great tribulation such as has not occurred since the world's beginning until now, no, nor will occur again. In fact, unless those days were cut short, no flesh would be saved; but on account of the chosen ones those days will be cut short. - Matthew 24:14-22 (CLICK for complete scriptural reference)