Not necessarily. Depends on the IOs currently rostered at the CPC. In any case, the IO interviewing you will have a checklist that s/he will be filing upon your interview, which will have all your processing info. It is the longform that you'll sign on that day as well. In which s/he will finally endorse his/her "approval" of your case / or "need further verifications" (God forbid). And s/he will tell you the outcome then-n-there*.
*E.g. My IO said that "she is done and is approving my case" during the interview day (Aug-24, 2018). The Oath letter that I received two weeks later states the date of approval as Aug-24, 2018.