That's a good point, a watcher. Armageddon does not just suddenly happen, in the JW version of things. It follows a period of anarchy and persecution that is so extreme that it would end humanity without God's intervention. Maybe the teaching of the Great Tribulation is even more of a problem for the WTS than Armageddon itself. Because if they ever claim that we are in that time, then it is a period of time that has to get worse and end with Armageddon. If things improve or stabilize for a time, then they would be wrong.
In other words, there is a beginning of the end in their worldview, and it should be so extraordinary as to be identifiable. There shouldn't be any hesitation on their part, no "these events might be the start of something." Everyone should be able to recognize that this is something unprecedented and meaningful. Until that happens, it doesn't matter how close the Day of Jehovah is... it hasn't begun.