I thought CT Russell was the brains behind the 607/1914 nonsense...Is that not correct?
CT Russel had rejected Adventist chronology and date setting prior to meeting Nelson Barbour in 1876. (I am paraphrasing the July 15, 1906 issue of Zion's Watch Tower where Russell himself explained all of this at length.)
Barbour taught that the Gentile Times were a 2520 year period running from 606BC to 1914AD; that an invisible presence of Christ had commenced in 1874 and that there would be a 40 year harvest culminating in 1914, which would see the start of the Millennium.
Barbour had outlined this chronology in his own periodical, Herald of the Morning in 1875 and Russell was so intrigued by it, that he paid Barbour's expenses to meet with him and explain it further.
Convinced of Barbour's reasoning, the two men jointly published Three Worlds And The Harvest Of This World, which explained the chronology in book form.