AMG: there is a lottery held at both 0800 and 1100 each day for walk-in permits. The first is for same-day entry, the second is for next day entry. You can show up anytime after 1100 to try and get walk-in permits, but there is no way of knowing availablility after the initial rush at 1100.
Essentially, the 0800 lottery takes care of any remaining permits from the previous day.
-L
