FYI, "waiting for signature" is a status, when all the required info is rec'd a person is moved to that status, then there are several variables that determine how long a person could sit in that status, I have seen days to many months in the status, the NRD does not play a role in this, NRC does not process one NRD's over another or in any order it is just as they get to them.
The date they put to have all documents to NRC is to help figure out numbers for the next board and plan OCS classes, for example if there are 10 spots each for SNA/SNFO/SWO and you have 10 people all pro Y for SNA/SNFO/SWO, if they don't figure out who is taking what then the numbers will be off on the next board because they won't know how many of those 10 are going to each designator.