I would say that this process is frustrating for almost everyone who goes through it even the most patient ones. I’m not patient though
From my experience, the investigator will usually reach out to you first to introduce themselves, let you know what is going on, and confirm some basic information over the phone. The background investigator then goes out to your area and begins calling/then visiting the references (this includes people on your SF86 form, and developed contacts - those are people who are not on your SF86 form… sometimes some people on your SF86 form never get contacted).
Your BI interview happens during this process (beginning, middle or end … it really depends on the investigator).
Hope this helped out!