I have a bunch of WN flights booked through the holiday season and really want the fast lane as I'm traveling with my family. I just called SW to add our Trusted Traveler #s to our reservations. A little concerned that it may not apply to existing reservations--is info submitted to TSA for screening only at time of booking? The SW agent didn't seem to know.....
FROM SW's TSA Pre-check email:
"Note: Only reservations booked after opting-in are eligible for TSA PreCheck.
Trusted Traveler participants will need to provide their CBP-assigned PASS ID number in the "Known Traveler #" field during the booking process at southwest.com® and swabiz.com. The passenger’s Trusted Traveler information will be submitted along with reservation information to TSA’s Secure Flight system."