Probably not "wonderfully knowledgeable", but I'll try!
LOA's and principal nominees should be handled as they come in. My son (with an LOA) was notified of his nomination on Dec 14, was called a few days later and told his appointment would go out shortly, and received it on Dec. 26. I think for either of those cases, once they meet the requirements (usually physical or nomination for LOA or 3Q'd for principal nom), the appointment should go out right away. I think of these all as being in a separate "stack" just waiting for the last puzzle piece and then getting them out (and off their desks!) as fast as they can.
For a competitive nomination, yes, they have to wait until all 10 names on the slate are in and their applications are complete in order to determine who has the "best" score and offer them the appointment. From what I understand (and this is more for WP I'm sure about, not certain if AF does it the same), then they have to wait for ALL the slates to be done in order to get everyone remaining into a rank order for the National Wait List. I know WP then takes a minimum of 150 from the NWL and offers them appointments. I don't know how AF does it at that point.
But I don't picture it as a big stack just waiting. More like a bunch of little stacks and as soon as one is ready (all 10 applications are in), they grab that one and jump on it. And I'm sure the NWL is being filled in as they go (same for each little pile), so each time they're just waiting for the last thing, not starting looking at a file for the first time once the last one in that group comes in.
So it seem like the timeline is that if you have a principal nom or LOA, you should know soon (ie, get the appointment). If you're the top on the competitive slate, you'll be next to know, as soon as your slate is done (may be a wide variance in time here). Getting an appointment from the NWL would be next, followed by getting one because someone else declined theirs and you were next on the list (either NWL or an individual slate). However, I don't know when/where actual "Rejection letters" (TWE's) come in during this process - seems like for Navy it's sometime in April - not sure about the other academies.
Good luck!