blondie, one of the very first WT books my JW father studied with my sister and I (my sister and I were very young children at the time) was the 1958 WT book called From Paradise Lost To Paradise Regained. I have a hard cover print edition of that very old book published from well before 1987. [That copy which I currently have says "3,250,000 Edition" and is in excellent condition; I bought it to replace my first copy (which my sister and I previously shared) because its cover had become very worn and because my sister had colored in some of the pictures. I am confident that the text is the same in both editions.]
In paragraph 7 of chapter one (on page 10) the book says the following. 'The time had now come to start getting the earth ready for the animals and humans that would later live on it. So a period began that the Bible calls the "first day." That was not a day of twenty-four hours, but was instead 7,000 years long.' The next sentence on the page is the start of paragraph 8 and it says the following. "During this first creative day the cloud of darkness was taken away from between the earth and the sun. Paragraph 11 (on page 11) says: "But during the second creative day of 7,000 years Jehovah God caused a division between the ocean and the clouds." Paragraph 20 (on page 13) says 'When the fourth creative ended, 28,000 years had passed since God said; "Let light come to be," and since God had begun preparing the earth for living creatures.'
The second paragraph of chapter two (on page 18) says the following. "It was near the end of the sixth creative day. This means that nearly 42,000 years had passed from when God said: "Let light come to be." Five creative days of 7,000 each had gone by and now the sixth day was almost finished.'
Another WT book I studied with my sister, with our father conducting the study, was the 1969 WT book called Is the Bible really the Word of God? That was one of the key WT books which convinced me to become baptized in the early 1980s. I still own the copy of that book (which is "First Edition, 3,000,000 COPIES") which I obtained as a preteen child. Chapter 2 of that book is called "Genesis Account of Creation --Fact or Fiction?" The first full paragraph of page 19 (part of that chapter) says the following. 'So it is plain that the word "day" can be used to refer to a twenty-four-hour day, a person's lifetime, 1,000 years or even longer. In fact, on the basis of the length of the seventh "day," there is reason to believe that each creative period or 'day" was 7,000 years in length.' In my copy of the book I have a note that my sister, I, and my father studied that paragraph on "6-6-78".
The "Revised 1970 C.E." edition of the 1961 copyright NWT on page 1461 in the "TABLE OF THE BOOKS OF THE BIBLE" in the column called "Time Covered (B.C.E.) says the following regarding the events of the book of Genesis: "After 1:2: 46,026-1657". [By the way, my oldest copy of that NWT edition is the one I used to give my very first kingdom hall talk, a Bible reading with introduction (though my mother wrote the introduction for me), when I was only 8 years old - years before I became baptized]. Notice that this 1970 Bible edition says the first creative day began 46,026 years before the common era, thus indicating that according to the WT 48,000 years would be completed in the year 1975 C.E. (46,026 years plus 1975 years minus one year [since there was no year between 1 BCE and 1 CE] equals 48,000 years). Adding a future 1,000 year portion for the reign of Christ would make a time period equal to 49,000 years, which would thus consist of 7 creative years of 7,000 years each.
The above are just a few examples showing that before the year 1980 CE that the WT for more than a decade taught that each creative day was 7,000 years long - not 6,000 years long. Furthermore, I remember reading in a volume of Studies in the Scriptures that Charles Taze Russell taught that each creative day was 7,000 years long.