Originally Posted by
HkCaGu
Your flight is effectively not going to arrive early. IIRC USCBP opens at 6. If multiple flights release passengers at the same time, UA won't be parking at a TBIT gate favorable to passengers running to USCBP. It's going to be a southern gate easiest for towing back to T7.
And then there's TSA and the long walk/ride to T7 (and you have several choices of routes). Boarding time for a 0700 B777 is 0610.
If that flight comes into TBIT, I'd drop my estimate from 3% to 0.03%. I can never remember which flights go through customs at T6/T7 and which go through TBIT.