Great question…it varies considerably by unit. For the boards I chaired, we made an effort to provide a response to each candidate who submitted a package, both interview-selects and non-selects. This could come in the form of a generic email, or a personal phone call from the hiring POC. The process each unit uses depends on several factors: how many packages were submitted, available manning in the hiring office to make phone calls, etc. We tried to maximize the “personal touch” as much as possible, knowing the effort applicants made to submit an application. We always wanted to honor that.
As far as the timeline for making that decision goes, this is also heavily dependent on similar factors: the overall number of packages, screening process (what criteria are used to score packages—manual scoring, MilRecruiter sorting tools, or more-likely a hybrid of both), availability for part-time hiring offices to make these determinations (over drill/UTA weekend), etc. Think of boards happening in monthly Drill/UTA cycles…we’d want to give at least one month to process applications/make cut-lines/develop interview lists, and another month for interviewees to prepare. You *should* have at least one month from invitation to interview, under normal circumstances.
Bottom line: you’re not out of line to politely ask the unit’s hiring POC when you could expect a decision. 1) it’s their job….2) even in a small way, you’re demonstrating enthusiasm for that particular unit, which even if “non-select” is your outcome, building name-recognition for yourself may lead to better success at a later board attempt with that unit.
Hope this helps!