I attended two AIMs this weekend, and the regional commander (Maj. D.) stated that all LOAs were allocated at the beginning of September. There will not be any additional sent out for the Class of 2016.
Applicants for the Class of 2016 are of very high caliber, all with outstanding files. There are certainly many more qualified than will be offered appointments. He stated that if you don't get a nomination from any of the sources, you may still be one of the 300 offered appointments from the NWL. He relayed a story from last June where he tried to contact a candidate the Thursday before R-Day, but the person was not available due to his being on vacation in Korea; he was not reachable. So the appointment was offered to the next person on the list on the Friday before R-Day.
He himself got his appointment in late May (a Class of 2001 WP grad), and mentioned that Col Endres, head of WP Admissions got his appointment a few days before his R-Day.
All potential applicants were encouraged to take SATs and ACTs frequently, to open their files as soon as possible, to apply to attend SLS, and to get their files completed as early as possible. Also advised that before the end of your Junior year, to get your transcripts on the way to West Point; and to have ready access during the summer to your college counselors and teachers you plan to use for references. Those who complete their file before their senior year starts have the best chance to get an LOA.