Was FDS chosen before the Sanctuary was cleansed ? see what Rutherford says :
From Golden Age 1935 page 446 from a series of articles about God’s Calendar and Timepiece, a turgid and complicated argument to support Rutherford’s view of prophecy and chronology.
" (Saturday, October 15, A.D, 1932), there was published in The Watchtower a resolution, publication of which was official notification that then and there ended the 2300 days of Daniel's prophecy.
(Daniel 8 : 14) It pleased God to thereafter have a cleansed sanctuary. Since then God's people have had peace in God's temple. This as the occasion for the naming of this month.
"And all thy children shall be taught of Jehovah; and great shall be the peace of thy children."-Isaiah 54 : 13, A.R.V"
So,according to Rutherford the 1919 choosing could not have happened, not untill 1932, not that he linked, in this article, the "cleansing" with a choosing of a FDS as the modern day GB do.