The WTS always covers its a** by having 2 contradictory teachings. Thus it would not be possible to determine that the end was close; that it would come at a time you think not (per Jesus).
While they teach BTG has fallen and the waters are drying up (don't hear that too much lately), they also teach that BTG will go down quickly as a going concern, as a queen, like a vase that is suddenly knocked off a pedestal. Notice that this reasoning was given in 1974 when BTG was not disintegrating at the speed some JWs thought since 1975 was just around the corner.
***w74 1/15 p. 54 "Keep Close in Mind the Presence of the Day of Jehovah" ***
But what does Jeremiah 25:34, 35 say about this? Concerning what will happen to Christendom's leaders just as concerning what was to befall the Jewish leaders shortly after Jerusalem's fall in 607 B.C.E., it says: "Howl, you shepherds, and cry out! And wallow about, you majestic ones of the flock, because your days for slaughtering and for your scatterings have been fulfilled, and you must fall like a desirable vessel!"
So it is not a slow fading away by loss of members that brings the end of Christendom?s false religions and their clergy. Instead, just as a beautiful vase, a "desirable vessel," suddenly falls from its pedestal, to the dismay of its onlookers, so the clergy and their false religion have a sudden, surprising crash to destruction.
Also, as to the swiftness of the fall of Babylon the Great, what does Revelation chapter 18, verse 10, say: "They [the mourners, including many commercial men] stand at a distance because of their fear of her torment and say, 'Too bad, too bad, you great city, Babylon you strong city, because in one hour your judgment has arrived!" And then, in verse 21, it continues: "And a strong angel lifted up a stone like a great millstone and hurled it into the sea, saying: "Thus with a swift pitch will Babylon the great city be hurled down, and she will never be found again." Appreciation of this fact can protect us against any inclination to 'put off' the day of Jehovah simply because Babylonish religion still exercises considerable influence in some areas.