Later, they said creative days were "several thousands of years" long, so old JW'S would think "Yeah, 7 thousands" and young people with access to science at school would think "millions" and Watchtower would never admit they were previously wrong.
That's exactly what happened to me. The blue Creation book was instrumental in getting me to buy into the religion. I read it in the mid-90s and thought it was consistent with science, which taught the universe was billions of years old. I'd never heard of 1975 or the 7,000 year creative days it was premised on.
It wasn't until after I got dunked that a JW pointed out that the literature didn't say millions, it said thousands. He then specifically tied it to the former 1975 teaching. I was dumbfounded since being able to reconcile science and the bible had been the primary reason I'd bought into it. I was a naive and stupid teenaged at the time, but that's a separate story altogether.
This JW was an adult convert and really had no business being familiar with the 1975 debacle. He converted in the 90s and had no JW family. He must have been doing his own research on the side. A year or two later he moved away and faded. He was a smart guy. In hindsight it was probably inevitable.