Russell started by preaching that Christs second coming would be in 1873.
When it didn't happen he published the booklet on how Christs second coming would be invisible, based on interpreting PAROUSIA as presence - an invisible coming.
The coming in Kingdumb power would then happen in 1914 - the master's "arrival". Based on this the WT claims Christ appointed his "Slave Class" after arriving in 1919.
Then the beginning of the invisible presence was upped to 1914 - he arrived invisibly in Kingdumb power, but has not returned even invisibly to earth (see "Proclaimers" book)
So his coming still has not happened. But they said it has. No it hasn't.
So why do they claim that the Slave was appointed upon the master's arriving?
They now claim that Jesus "comes" at different times in different capacities.
This idea was jotted quickly - if i had time right now i would post the references. But i didn't want to forget it.
HB