Ok, I'm getting to the point I'm trying to make (I think):
TD, the author of the paper you linked to, says:
"It can be clearly seen from the period literature that the Witnesses' doctrine of God's kingdom as a heavenly government establishment in 1914 AD did not begin to emerge until the year 1920 and did not reach its final form until the year 1925." - page 42
I think that the statement found at the Watch Tower of May 1, 1914 proves that this isn't accurate. Russell did teach that God's kingdom as a heavenly, invisible government BEFORE October 1914, and not only after 1918/1920:
"Christ and the church have only been the incipient kingdom, an embryotic kingdom - the kingdom class, preparing for investiture of authority in God's due time, which we believe is now near. The kingdom is to be a spiritual one, and hence its rulers will be as invisible as are the angels and the heavenly Father. [...] During the Millennium, the Kingdom authority and power of God through Christ and the church will be exercised amongst men; and yet they will not see it with the natural eye, but merely with the eyes of their understanding."
Eden