According to the schedule on the Syfy.com website for the month of October, WWE Smackdown is listed as being on Thursday night at 8:00 p.m. ET beginning on October 2.
There was a report a few weeks ago of a WWE production truck displaying Smackdown in a new Thursday night time slot. WWE responded by saying the change in the production truck was "overzealous." What this means for NXT and Superstars is unknown as both shows air Thursday evening as part of the WWE Network.