Two of Watchtower's friends are elapsed time and poor memories.
Most JWs (and perhaps some on this board) aren't aware that the "beginning of the time of the end" year 1914 had a predecessor -- 1799. How Watchtower wriggled out of that 1799 date may help us understand how they will try to wriggle out of its replacement year, 1914.
What Watchtower said 125 years ago:
'As already pointed out in MILLENNIAL DAWN, the great prophetic period termed "The Day of His Preparation," began in 1799 and will end with 1914: and it is the advancement of this "day" and the light which God provides, necessary for its work, that has brought the wonders of the present, and is rapidly now bringing on the conditions for the great time of trouble, for the overthrow of present imperfect conditions and the establishment of the Kingdom of God's dear Son.' Zion's Watch Tower, July 1, 1897 p 194.
What Watchtower said 114 years ago:
'The “Time of the End,” a period of one hundred and fifteen (115) years, from A. D. 1799 to A. D. 1914, is particularly marked in the Scriptures. “The Day of His Preparation” is another name given to the same period, because in it a general increase of knowledge, resulting in discoveries, inventions, etc., paves the way to the coming Millennium of favor, making ready the mechanical devices which will economize labor, and provide the world in general with time and conveniences, which under Christ’s reign of righteousness will be a blessing to all and aid in filling the earth with the knowledge of the Lord.' Millenial Dawn, Thy Kingdom Come (1908) p 23.
Then -- What Watchtower said to wriggle out from 1799 some 15 years after 1914.
“For a long while it has been understood that "the time of the end" began with 1799 A.D. and con- tinued until 1914, and that the beginning thereof is specifically marked by the fact that Papacy at that time received a severe blow. While many facts seem to support that conclusion, the proof is not by any means conclusive. Such may have been a miniature fulfilment.” The Watch Tower, Dec 1, 1929 p. 355
Also:
“ Taking all these scriptures together, and knowing that they must be in exact harmony with one another, and taking the well known facts in connection therewith, it is easy to be seen that the definitely fixed "time of the end" was and is 1914 A.D. Nothing came to pass in 1799 that corresponds so well with these prophecies as did in 1914.” The Watch Tower, Dec 1, 1929 p. 357