Just my two cents gained from a quick reading of last year's thread.
I think that there is no need to panic at all till Initial Notification Date (Dec 15, 2015). In the last season, there were candidates who did not have their statuses change, but still received invites on Initial Notification Date. The way I see it, mind you I have not validated this, is that we will receive one of three decisions come Dec 15: invitation to interview, waitlist without interview or denial of admission.
All those who are interviewed will subsequently get their decisions on a rolling basis. I think this is a great strategy: by releasing their R1 decisions later than the rest in the top 15, Johnson would increase their yield without impacting class quality. Given a market where there are more qualified applicants than there are seats, Johnson would still be able to assemble a class of very accomplished students without competing with the other schools directly. Post the barrage of decisions from the other top 15 schools, it would simply be scooping up excellent candidates which somehow missed out (of course, assuming most of those who accept offers from others in the top 15 promptly withdraw.)
I think it's brilliant and unconventional - a lead-on from this is that they would be able to employ their scholarship money more effectively.