If you have all of your documents in order the day before the interview you will drop them off then. If not, then you will have a chance to get whatever is missing and bring the day of the interview. That happened to us. We didn’t have the medical results when we dropped off the documents so we brought it the day of the interview.
i believe you can change the location of the document pick up on the visa website where you paid for the biometrics appointment but they give you the location options. You have up until a certain date to change it I believe.
cookies has a in depth write up of the whole process on this thread that you should read up on. I will put together the questions we got in a post later today.