If they want to, they will say the great tribulation will have started.
........................................
BINGO!!! After all if Jesus took his throne in 1914, and he's decided to take 99 years (and counting) to actually start executing judgement, the arguement can be made that the GT can START during the overlapping generation, but is there any restriction on how long it can actually last?
Future WT quote decades from now:
"In the early 20th century, even events as extreme as World War I were not enough for human goverments and their followers to realize these momentous events were a visible sign that Jesus Christ had cast Satan and his demon followers out of heaven and taken his seat as his throne. So today too, Satan continues to 'blind the minds of the unbelievers' (2 Cor 4:4), not allowing them to realize that the world conditions we see around us today are in fact a visible sign that the foretold Great Tribulation has already begun. Although Jehovah has not revealed the exact length of the Great Tribulation, we can have confidence that as he directs his earthly organization through these historic events, that He will continue to provide life-saving "food at the proper time" through his Faithful Slave (Matt 24:45). How important it is, then, that we stick close to and listen to the Faithful Slave to ensure we remain in God's protection as this Great Tribulation we're experiencing becomes evident to all mankind. Without such vigilence, we become like those in Noah's day who 'took no note' (Matt 24:39)."