The ONLY item of your DS's application that directly involves the BGO is the BGO interview. One item out of roughly 10. Thus, if other kids "are way farther along," that tells me your DS hasn't completed the other items. So he needs to get busy.
I totally agree with NavyHoops. I don't want to interview candidates until they've turned in at least some items over which they have control (essay, CFA, activities record, transcript, etc.). It always amazes me that candidates want the BGO to conduct an interview before they've done anything themselves. I can almost guarantee that, if DS is more than 75% done with the other items in the package, a BGO will contact him.
There is also PLENTY of time. The application deadline is Jan. 31. It's only mid-September. While I'm not suggesting anyone wait until the last minute, many successful applicants complete their packages in October, November and December. Finally, if DS needs a MOC nom, most of those decisions aren't made until December. So, for most candidates, finishing their application now isn't going to speed up the overall process. I'm NOT suggesting candidates put off completing their applications . . . but not being finished on Sep. 15 is not a huge deal.