They have incorrectly predicted the end date numerous times, most recently 1975.
They claim they predicted the last days would start in 1914, which is not correct. They originally predicted the last days would end (not start) in 1914, which the believed would result in the end of the world. It was only after nothing happened in 1914 that they started claiming it was now the start of the last days. And the whole 1914 date was based on an incorrect date for the fall of jerusalem anyway.
They are still stuck on this 1914 date, even though it makes their original claim that the generation alive in 1914 would not pass away before the end to be patently ridiculous. They have tried to cover this by saying that "this generation" can now be overlapping generations, which is even more ridiculous. By that reasoning the last days could last hundreds of years by just adding more overlapping generations.