Originally Posted by
NY-FLA

I know of no US airlines that issue BP's 24 hours prior to departure of the first flight-leg of the itinerary. (Issue BP=OLCI). Again, I believe this is limited by TSA.
Lots of airlines issue BPs prior to t-24 hours, but only for connecting flights. I know CO, DL, NW, and US allow OLCI BPs to be issued for connecting flights > 24 hours out at t-24 hours for the first segment.
What logic makes the 24 hour requirement necessary only for first-leg flights?