It would be great if a WT reference to this teaching could be found.
"Ask, and ye shall receive".
https://wol.jw.org/en/wol/d/r1/lp-e/1999323#h=14:0-15:594
God’s people once understood that the first phase of the great tribulation began in 1914 and that the final part would come at the battle of Armageddon.
However, in later years we have come to see things differently. On Thursday, July 10, 1969, at the “Peace on Earth” International Assembly in New York City, F. W. Franz, then vice president of the Watch Tower Bible and Tract Society, gave an electrifying talk.
Then a significantly adjusted explanation was offered: “To correspond with the events of the first century, . . . the antitypical ‘great tribulation’ did not begin in 1914 C.E. Rather, what took place upon Jerusalem’s modern antitype in 1914-1918 was merely ‘a beginning of pangs of distress’ . . . The ‘great tribulation’ such as will not occur again is yet aheadYou can get a whole long list of "clarifications" here:
https://wol.jw.org/en/wol/d/r1/lp-e/1200277174#h=1:0
"Let the reader use discernment" as to which is wackier - old beliefs, or current beliefs.