Timing for BGO interviews depends on the BGO and on you. We are "required" to do them once a student has >33% of his/her packet submitted. Some wait until this time because, quite frankly, many candidates in our system will end up not completing their application and BGOs don't want to "waste time" interviewing people who don't need to be interviewed.
Other BGOs may try to do all their interviews as early as possible, often in the summer, when candidates aren't in school and schedules are more relaxed. I have done them earlier this year than I usually do b/c I've had a couple of candidates who have most or all of their packets in.
IF you have most of your packet in, you should be hearing from your BGO. If you don't hear, you may want to reach out to your BGO. Be gentle.

Do remember that all BGOs are volunteers, many hold down full-time jobs, and we often travel on business and/or take vacations. So, if you don't get an immediate response, don't panic. Wait a week or so and send another gentle note.
Having an interview in October is fine. I've done them as late as January. The only thing I will add is that USNA typically doesn't review your packet until it is complete, including your BGO interview. So, if you do have everything in, be sure to contact your BGO so you can get your interview done.