Originally Posted by sannmann

Usually, yes. Might book a couple weeks out and ticket once the travel authorization is finalized. A booking can be made before the travel authorization is approved but the booking may not be ticketed until the authorization is approved.

Originally Posted by drewguy

Yes. As soon as you have a travel authorization (or even sooner) you can make a reservation. It's held until ticketed, typically about T-72.

Sometimes the ticket is purchased earlier, but not on United - only when it's a non-contract carrier that requires advance purchase or won't hold ticket. The deal with contract carriers I believe requires them to allow this.

It's a bit weird on UA website - it will allow seat selection on the website, but reservation will show as "reservation expires [tonight at midnight]" but is updated each day! One can't use mobile app to change seats. And of course until ticketed one can't request an upgrade.

FWIW, my understand of the rationale for this approach is that previously when purchased immediately too many unused tickets weren't getting cancelled and refunded. The traveler didn't care (no expense to him/her) and the agent and person responsible for booking didn't always track these things. Of course the airlines weren't exactly quickly paying back the money for unused tickets.