When I ordered a batch of small two-layer boards from them last winter there was a long lag between order acknowledgement and the start of fabrication. Not so with this board.
The order I submitted to PCB-Pool Monday evening specified an eight working-day lead time. Four working days in, the board has already been laminated, drilled, plated and etched. All that's left is the application of the solder mask and silkscreening, and routing the board from the panel. Oh, and the critical electrical test, to make sure the thing is usable.
My guess is that they started it earlier because it's a larger 4-layer board instead of a set of small 2-layer boards, thus requiring more preparation if it failed the e-test. They have a good track record for on-time delivery, and this would be one way to keep it.
They've been sending me photos of the board's progress as part of their "Watch-UR-Board" program. I'll post some of them tonight.