Judging from the title of the book "Jehovah Has Become King," are you suggesting that Jehovah has become king already?

No, just the opposite, in fact. A large portion of the book is devoted to overturning the notion that Jehovah has already become king. As you may or may not know, the expression “Jehovah himself has become king,” and related expressions, appear in numerous passages in the Bible. Jehovah's becoming king has to do with him taking up power and commencing to judge his people and rule the world. The Watchtower has long taught that Jehovah became king in 1914 and in 1919. For example, in the last chapter of the book appears an excerpt from the first volume of the Watchtower’s Isaiah commentary, which says:

“In modern times, Jehovah ‘became king’ in 1914 when he installed Jesus Christ as King in His heavenly Kingdom. He also ‘became king’ in 1919 when he demonstrated the power of his kingship by liberating spiritual Israel from bondage to Babylon the Great. Jehovah will again “become king” when he brings an end to Babylon the Great and the rest of this wicked system of things.”

Contrary to the Watchtower’s assertion that Jehovah has already become such, Jehovah becomes king during the bleakest period in mankind’s dark history. The intention of the book is not merely to overturn the Watchtower's 1914 chimera but to also put forth from the Scriptures what Jehovah's becoming king will mean for Jehovah's Witnesses. But, while it remains a future event, it appears as if conditions are ripe for things to begin to unfold that will lead to Jehovah becoming king in the fullest sense.