That's a very good question, because it calls up a frank discussion of what is called the doctrine of "Imminent Return." Simply put, that is the view that Jesus could make His Second Advent at literally any moment. In order for this to be possible, however, several scriptural pre-requisites must have happened already, and therein lies the rub.
Among these pre-requisites is the fulfillment of Jesus' own self-constraining, prophetic declaration, "And this gospel of the Kingdom shall be preached through the whole world as a witness to all nations, and then the end shall come."
-- Matthew 24:14
Jesus himself declares that he's not coming back until after the task of evangelizing the nations — commonly known as 'The Great Commission' — is completed. In order for Imminent Return doctrine to be true, that task must have been done already.
Of course, every missions organization can tell you at great length just how incomplete that task is, and they can tell you about how long they think it will remain incomplete.
Still, there are some who, by clever interpretations of what is meant by "the whole world," and who is included in "all nations" claim that this task was actually completed in the first few centuries of Christianity. Generally, this means "the whole world" is roughly equal to "the Roman empire" and only the nations under the empire are part of "all nations."
The Reformers of the 16th century, however, understood "the whole world" to mean "that part which is dwelt in"; every inhabited place, which is the plain-sense reading of the text, and therefore most credible.
So, there is a disparity, and how one resolves the disparity influences whether or not one may subscribe to the doctrine of Imminent Return. I happen to agree with the Reformed view, and am not, therefore, an adherent to Imminent Return doctrine.
For my part, I see a coming coincidence of several pre-requisites happening over the next 10 to 20 years; more or less. You note that Jesus only says the one task will be completed and then the end will come; he doesn't say how much time will elapse between the completion of the Great Commission, and the end.
So, I see the completion of The Great Commission, bringing in the last of the Gentiles, and that triggering the Restoration of Israel with a revelation of Jesus as Messiah that finally evokes the long-awaited cry, "Blessed is He that cometh in The NAME of the LORD!" which I expect will erupt simultaneously with Jesus' glorious appearing in the sky.
You may recall that Jesus made the prophetic declaration over Jerusalem in Matthew 23:39, "For I say unto you, ye shall not see me henceforth until that ye say, Blessed is he that cometh in the Name of the LORD." So I think when that cry rings out, Jesus will be seen again in Jerusalem.
Exactly how long that all takes to work out; I do not pretend to know, but I am convinced that it will be a matter of some years or a few decades, not centuries more.
Ah, but here I've been going on all this time. What do you think? I look forward to your post.
And this gospel of the Kingdom shall be preached through the whole world as a witness to all nations, and then the end shall come." -- Matthew 24:14
To me, IMHO, this occurs during the 7 year tribulation period. A lot of the work is done by the 144000 Jewish evangelists.The end spoken in this verse would be Our Lord Jesus Christ's Second Coming return at Armageddon and the Kingdom would be the millennial one.
I personally do follow the imminent return idea fairly literally. I do try to live in the now. It is kind of easy one day at a time. You get up and say This is the day the Lord has made Let us rejoice and be glad in it! If the rapture happens today that would be cool!