The Admissions Board typically holds its first meetings in late August. However, there can be a backlog so, just b/c your application is complete, don't assume it will be reviewed at the next board. This holds true throughout the year.
Your BGO interview is typically the only admissions interview you will do. They try not to review your record until it's done. However, if your packet is otherwise complete, and has been for several weeks w/o a BGO interview, and there's no evidence that the candidate is the one holding up the interview, they may go ahead without it.