I mean, when I thought about it - they are running the Impressive Influence buff through the end of September. Doesn't make sense to have it last until a day after pre-patch, when a lot of returning people would find out the buff was disappearing in less than 24 hours. Better to have it end, pre-patch launch, and avoid the topic alltogether.
October 6th is my new guess if I had to make one. It has to be the 6th.