There are a few times this was said:
THE END WILL BE IN OUR 20TH CENTURY
Awake! 1961 Feb 22 p. 7
That now-operating kingdom in heaven will, within the twentieth century, cleanse the entire earth of wickedness... Can you not see that the twentieth century is the century indicated by the prophetic language of Matthew 24, Mark 13, Luke 21, and 2 Timothy 3?
Awake! 1961 Feb 22 p. 8
...is it not only logical that whatever else is recorded in these above-mentioned Bible chapters must also come upon the twentieth century? ... Revelation 16:16 calls it the "war of the great day of God the Al mighty," Armageddon. This war will come in the twentieth century . ...Now is the time to heed Bible prophecy concerning the twentieth cen tury and live forever in the sunshine of God's new world.
Awake! 1962 July 22 p. 32
But how many realize that it contains information of special interest to those of us who live in this climactic
twentieth century ?
The Nations Shall Know That I Am Jehovah p. 216 "Shortly, within our twentieth century, the "battle in the day of Jehovah" will begin against the modern antitype of Jerusalem, Christendom."
Watchtower 1984 March 1 pp.18-19 "Some of that "generation" could survive until the end of the century. But there are many indications that "the end" is much closer than that!"
Let Your Kingdom Come 1981 p.11 ...now in our 20th century, we have come to the time for harvest — "a conclusion of a system of things, and the reapers are angels"!
Watchtower 1989 January 1 p.12 (loose copy magazine): "He was laying a foundation for a work that would be completed in our 20th century. "