Interesting: Already Mrs. Russel misinterpreted that the Faithful slave was a kind of "leader" or messenger, her husband, a real man, she misunderstood it as a prophecy, and not as parable what it is. Later it was broadened to mean all members of the class of heavenly hopers,
only in the last year they decided to minimize the prophetic adaption unto the GB-Leadership itself alone again.
Didnt Rutherford say already himself that the proclamations at the conventions since 1922 were fulfillment of prophescies. I should check this.
The origin of the belief that everything has a fulfillment from 187.. onwards until ....the end... but beginning in the 19th century is a "belief" that is shared - was shared - by many other groups at that time. I lately looked at the prophetic timetable that is published by messianc jews. They believe similar things only that everything has fulfilled since the time when Jews are returning to Israel, a belief that was hold by Russel too btw.