I think I might be able to be of some help here!
It seems like the program is holding three interview dates from what I am hearing so far- 11/17, 12/1, and 1/12. The administrative director of the program emailed me back stating that all of the responses to DPT applicants for this cycle are anticipated to be sent out by mid-late January, meaning that I think the 1/12 interview date is the last official one. I am unsure though, and I am also unsure of how it works after those dates - maybe applicants who were not invited to interview will be invited to a later interview date if the class has not been filled? I read from the Columbia '19 thread that some applicants were placed on an "alternate list" which I am assuming means waitlist and then were given percentages.
However, it does say according to some acceptance letters that the class will not be finalized until March (also according to that thread). One of the people even got accepted in late April apparently. DO NOT LOSE HOPE!