Originally Posted by
CDKing
Ive always been under the impression All existing reservations are submitted to the TSA and precheck eligibility verified at 72 hours. All new reservations after 72 hours are submitted for at time of booking. Also any existing reservations that have secure flight data changes between 72 hours and check in are resent to TSA.
That may be true, but the Pre-Check decision criteria is applied at check in. There's also a random component to those who are (otherwise) eligible. For OPSEC reasons, it would be a really bad idea to do this in advance.