Unfortunately the reason Rutherford came up with 1919 was not because of some divine prophesy - it was for a much more down to earth reason.
Rutherford had taken over the organization Russell had began. Many considered Russell as the faithful slave and many split off and continued as Bible Students in order to continue to follow Russell's teachings. Rutherford needed to establish that he was the one everyone now needed to follow. So, he came up with a new direction for the organization (including lots of BS about prophets returning from the dead in 1926) and it was decided that Jesus did not even choose his people until AFTER Russell had died....
There was nothing spiritual about it, it was just part of the political power struggle within the organization at that time.