From the WT CD 2003:
***w68 8/15 pp. 500-501 Why Are You Looking Forward to 1975? *** 1975! . . . AND FAR BEYOND! 34 Bible chronology is an interesting study by which historic events are placed in their order of occurrence along the stream of time. The Watch Tower Society over the years has endeavored to keep its associates abreast with the latest scholarship that proves consistent with historic and prophetic events recorded in the Scriptures. Major problems in sacred chronology have been straightened out either due to fulfillment of Bible prophecies or by reason of archaeological discoveries or because better Bible translations convey more clearly the records of the original languages. However, several knotty problems of chronology of a minor nature are not yet resolved. For example, at the time of the exodus from Egypt when Jehovah changed the beginning of the year from autumn time on the secular calendar to spring time on the sacred calendar, was there, in the Jewish calendar, a loss or a gain of six months??Ex. 12:1, 2.35
One thing is absolutely certain, Bible chronology reinforced with fulfilled Bible prophecy shows that six thousand years of man?s existence will soon be up, yes, within this generation! (Matt. 24:34) This is, therefore, no time to be indifferent and complacent. This is not the time to be toying with the words of Jesus that "concerning that day and hour nobody knows, neither the angels of the heavens nor the Son, but only the Father." (Matt. 24:36) To the contrary, it is a time when one should be keenly aware that the end of this system of things is rapidly coming to its violent end. Make no mistake, it is sufficient that the Father himself knows both the "day and hour"!36
Even if one cannot see beyond 1975, is this any reason to be less active? The apostles could not see even this far; they knew nothing about 1975. All they could see was a short time ahead in which to finish the work assigned to them. (1 Pet. 4:7) Hence, there was a ring of alarm and a cry of urgency in all their writings. (Acts 20:20; 2 Tim. 4:2) And rightly so. If they had delayed or dillydallied and had been complacent with the idea the end was some thousands of years off they would never have finished running the race set before them. No, they ran hard and they ran fast, and they won! It was a life or death matter with them.?1 Cor. 9:24; 2 Tim. 4:7; Heb. 12:1.