There were a couple of nice surprises:
(1) There isn't a separate chair of the meeting/exam, which means one less pair of eyes staring me down.
(2) The room is just downstairs from my lab, rather than in a stuffy building on the upper campus, which means familiar territory.
(3) The grad secretary at the department commented on how it looked like one of the longest essays she's seen for a prelim exam, implying that I put lots of effort which should work in my favour.
And now, for real this time, sleep.