You can find more info from Alan Feuerbachers essay here: http://corior.blogspot.com/2006/02/part-3-statements-concerning-1918-1925.html:
At the Baltimore assembly Brother Franz in his closing remarks made some interesting comments regarding the year 1975. He began casually by saying, "Just before I got on the platform a young man came to me and said, 'Say, what does this 1975 mean? Does it mean this, that or any other thing?'" In part, Brother Franz went on to say: 'You have noticed the chart [on pages 31-35 in the book Life Everlasting -- in Freedom of the Sons of God]. It shows that 6,000 years of human experience will end in 1975, about nine years from now. What does that mean? Does it mean that God's rest day began in 4026 B.C.E.? It could have. The Life Everlasting book does not say it did not. The book merely presents the chronology. You can accept it or reject it. If that is the case, what does that mean to us? [He went into some length showing the feasibility of the 4026 B.C.E. date as being the beginning of God's rest day.]
'What about the year 1975? What is it going to mean, dear friends?' asked Brother Franz. 'Does it mean that Armageddon is going to be finished, with Satan bound, by 1975? It could! It could! All things are possible with God. Does it mean that Babylon the Great is going to go down by 1975? It could. Does it mean that Babylon the Great is going to go down by 1975? It could. Does it mean that the attack of Gog of Magog is going to be made on Jehovah's witnesses to wipe them out, then Gog himself will be put out of action? It could. But we are not saying. All things are possible with God. But we are not saying. And don't any of you be specific in saying anything that is going to happen between now and 1975. But the big point of it all is this, dear friends: Time is short. Time is running out, no question about that.
'When we were approaching the end of the Gentile Times in 1914, there was no sign that the Gentile Times were going to end. Conditions on earth gave us no hint of what was to come, even as late as June of that year. Then suddenly there was a murder. World War I broke out. You know the rest. Famines, earthquakes and pestilences followed, as Jesus foretold would happen.
'But what do we have today as we approach 1975? Conditions have not been peaceful. We've been having world wars, famines, earthquakes, pestilences and we have these conditions still as we approach 1975. Do these things mean something? These things mean that we're in the "time of the end." And the end has to come sometime. Jesus said: "As these things start to occur, raise yourselves erect and lift your heads up, because your deliverance is getting near." (Luke 21:28) So we know that as we come to 1975 our deliverance is that much nearer.'
By the next year expectations were high. The following is taken from a talk entitled "Serving with Everlasting Life In View," given at a circuit assembly in the spring of 1967 in Sheboygan, Wisconsin by a representative of the Society. The speaker emphasized the nearness of Armageddon and specifically said that it would come before 1975. Speaking of the world to come after Armageddon, he said:
Well, now, who will be there, of us here tonight? For the Society has made application of this scripture, in pointing out that those of us among Jehovah's Witnesses that are not regularly associating with his people, without good cause, such as being flat on our back, will not be in the new order. And we're the ones that are going to come around when the doors close, and say 'I want in now. Sir, open to us!' And Jesus will have to say, 'I'm sorry, I don't even recognize you.' Now wouldn't that be an awful thing. Do you see now why the Society implores us, year in and year out, the same old thing, 'Brothers, get in the flock. Don't let any excuses get in our way. Nothing of any nature. There's only one thing that's going to count when that time comes, and that's that we are inside.' And we hope that all of us here tonight are going to listen to the Society's imploring. We're going to listen to the agonizing entreaty, 'Brothers get in!', because they know what's coming. And it's coming fast -- and don't wait till '75. The door is going to be shut before then.