"1919 governing body was chosen by Jesus, if this all falls apart then the GB lose all credibility"
Not true at all.
Sam Herd was born in 1934 and he is the oldest of the governing body so the governing body could not have been chosen in 1919.
In case you didn't know the GB of today is not the same as the one in the 80s and 70s. Prior it was the board of directors of the WTBTS.
Jesus didn't choose a Governing body or a board of directors. He observed people back in the early 1800s that were searching for truth in the scriptures. They searched chronology. Brown, Clinton, Bowen, Elliott, Barbour and Russell, Jesus saw them going in the right direction and observed and aided them. The GB doesn't need credibility because of 1919. 1919 was from that convention that they had then not because of chronology.
You all do know that the start of the gentile times is not based on the destruction of Jerusalem, as that was in 587. It was 20 years prior, in around 607. We don't know the exact event or dated that triggered the banding of the tree, stating that Russell was offbase for saying Oct 1, 1914 was the end,, but it is around that time.