See the quotes from the JWfacts link in the previous post.
The question is not what was 'explicitly written', but what was meant?
If you read all articles about 1975, and understand the mindset of the times, it is clear that the meaning was the 1000 years would begin about 1975. At the time, every JW received that message that was being given just as it was meant.
To say, "Well, it wasn't explicitly stated" is just gaslighting.
Besides some of it was pretty explicit.