This is how it was taught when I was young and making decisions that affected the rest of my life as many others did.
The 1974 Awake of April 8th shows how certain they were.
Under the subheading "Why Certain" Page 17
"Now we have reached the time when God will take action to bring about the full realization of all his grand promises"
"The Bible shows that this generation consists of those who were living in 1914"
Under the subheading "Coming Soon" Page 18
"When will it come?" Before the lifetime of the '1914 generation' runs out."
"How do we know that? Because this point was specifically mentioned by Jesus Christ as part of his prophecy for our times."
"The '1914 generation' has nearly run out, with most of the people who were alive then having already died. The remainder are of advanced age."
This was at a time when they also taught 1975 as being the end of 6000 years of the 7th creative day along with a thousand years being as one day to Jehovah and the last thousand years of the 7th creative day being a sabbath and a thousand year Jublilee Awake October 8th 1974
Both of these issues of Awake being special issues, I think.