it was stated that 1975 was the end of 6000 years of human history
R 350, and the sentence in the book finished: it therefore appropriate that the 1000 year would begin in that year.
That is a different issue to be dealt with because the Messianic Kingdom and the Millennium only address the consequences of the sin of Adam and Eve.
FM: Wt keeps harping on the sovereignty issue, and that is what they want the armageddon repeat mess cleared up during their (7X7) days senario, during the rest day too 6X1 =7 . That is why in wt literature the final test happens "at the end of the 1000 years" not after the count past 1000 is ended.
If you look at the jubilee year cycle, there is of course year 50, after the 49th year, 7x7 is finished.