USMAalltheway: Are you sure the MOC did not mean the academies issue appointments on a "rolling basis?" Because that is how the academies all issue appointments. The admissions boards meet throughout the year, beginning in late Aug or early September, assigning Whole Person Scores or Whole Candidate Scores (WPS or WCS) to each candidate, and sending out LOA's or appointments. Appointments cannot be sent out until the candidate has all things in place including nomination. MOC's typically let the academies know in Dec or Jan who their nominees are, then, appointments begin rolling out in earnest.
To be safe, I would contact your MOC (all three of 'em) with the very specific questions of how they handle this. America's Finest is correct in that there is no set way for an MOC to deal with this. I think it is most common for them to wait for the deadline. Often a committee meets, some are invited for interviews, etc. Truly, each MOC is different. I would go so far as to ask "Is it to my advantage to complete the packet early and have it in to your office well in advance of the deadline?" If you explain that you are trying to learn as much as possible about the process, they will likely be forthcoming with answers.
While you are at it, ask if they submit a ranked slate of nominations, a principal nomination with unranked alternates, or an unranked slate to the academy and get the next question you are going to have answered now. Just saying.............
All of this can be confusing. I would write my questions down before you make the call so you get it all straight. And then don't forget something and have to call back.