Hello,
The WT currently teaches that Jesus has been invisibly present since 1914. The old doctrine, from the WT, was not completely done away with at least up until 1943(God's Kingdom of a Thousand Years Has Approached, 1973, pp. 209,210). They originally taught that Christ's invisible presence began in 1874, and was 40 years prior to the end of the world in 1914. It seems that in the 1920's they began to shift from 1874 date where it was the beginning of Christ's presence, but the 1914 doctrine was being altered and fashioned, where it was kind of the consummation of His presence in which he would ready himself to rule and reign over this system.
"From 1874 to 1914 the prophecy concerning the Lord's coming was being fulfilled and could be understood, and was understood, by those who were faithful to the Lord and who were watching the development of events; but not by others." (Creation, 1927,[700,000 edition--back cover IBSA,p.310] [2,753,500 edition--back cover WT, p. 290])
They still were publishing that Christ's invisible presence began in 1874 and that the time of the end began in 1799(ibid. IBSA, p. 319/ WT, p. 298). Of course, these two dates have been discarded. The date 1914 is now taught to be the beginning of the time of the end, whereas it used to be taught that it was the ENDING of such. 1914 is also now considered to be the beginning of Christ's invisible presence.
The current teaching is that Christ returned in 1914 and after 3 1/2 years, an inspection of professed Christians was carried out. In 1918 Jehovah supposedly came to his spiritual temple with Jesus as his "messenger of the covenant". This was when "Christendom" was examined and rejected. This was also a time of testing for those associated with the WTBTS. God is supposed to have appointed a "faithful and discreet slave" class composed of anointed members of the Watchtower Society. Then in 1919 this organization is said to have "moved zealously forward to proclaim Jehovah's Kingdom by Christ Jesus as the hope for mankind."(Revelation-It's Grand Climax at Hand, 1988, pp.31, 32.
I hope that this helps a little.
Thank you,
David Race (ProveAll)