Got Lucky. Was going to be in SJ/Bay Area this Saturday night/SUnday. So booked hotel near SFO. Went in @ 1920 and saw sign saying they do up to 6 walk-in "a day". I also saw several people seeming to be waiting, so left. ($2 parking fee). Decided I would come back later in evening. Got there at 2255, no on sitting in chair, 1 person was just going in, waited a few mins CBP officer came out ask if had appointment. Said I did not, but hoping for walk in. Said they already did their 6, but there would be SHIFT CHANGE at 0001 (i.e. midnight) and may be able to get in then. Later another officer said the same. Several other folks showed up and got it during or before their appointment. At 2340 first officer came out again looking for scheduled appointments. When there was none he said, come on in! 10 mins or so later was done.

At the time there was 3 on shift. And just as I left one just came in (starting his shift I guess) There was 1 person that got there about 15 mins after I did and was waiting for the new shift.

So they CAN do more than 6 (I saw the clip board that shows the names) and it actually had something like 8 entries on it, which I assume was what they did that shift already, not including me. I guess just have to be nice and hope they are having a good day and might get in even if they have done 6 that shift. Also I think its helpful to be there just BEFORE the new shift comes in (at least seems to be on this weekend crew)

Good luck to all

Submitted Form on Web: 13
Conditional Approval: 6 Jul (earliest schedule available on that day was 29 Dec)
Approved in person: Saturday, 9 Jul

PS also guess I was really lucky cuz I didn't bring the Conditional Approval Notification letter. Just the schedule letter, but lucky was able to find me with my Passport. But they really need that 9 digit number in the letter.