For those asking about timing after you move from processing to preparing for shipment, this is what happened for me. I'm one of the last of the 5 minute club. My email from Apple acknowledging my order was received at 3.04AM Nov 30th 2012. Since I was spending so much money any way, I paid the extra $30 for 2-3 day "expedited delivery" (in other words, Fedex not UPS). Original delivery period: Dec 21-28 in 2-3 business days.
MY ORDER:
3.4GHz Quad-Core Intel Core i7
16GB 1600MHz DDR3 SDRAM-2X8GB
768GB Flash Storage
NVIDIAGeFrc GTX 680MX 2G GDDR5
APPLE MAGIC MOUSE
Apple Num Kybd(Eng)+User's Gd
MY SHIPPING RECORD: All times EST.
Th Dec 13, 2012 8.30 PM "Preparing for shipment" status noticed
Th Dec 13, 2012 10:12 PM Picked up SHANGHAI CN
Fri Dec 14, 2012 1:41 AM Left FedEx origin facility SHANGHAI CN
Fri Dec 14, 2012 6.44 AM "You have been sent a shipment" e-mail from the Apple Store. Estimated delivery (at that point) Dec 19, 2012.
Fri Dec 14, 2012 9:47 AM International shipment release SHANGHAI CN
Fri Dec 14, 2012 9:48 AM In transit SHANGHAI CN
Fri Dec 14, 2012 11:37 PM Arrived at FedEx location MEMPHIS, TN
Fri Dec 14, 2012 11:47 PM Shipment information sent to FedEx
Sat Dec 15, 2012 2:50 AM In transit MEMPHIS, TN
Sat Dec 15, 2012 4:00 AM International shipment release MEMPHIS, TN
Dec 16, 2012 4:06 PM Departed FedEx location MEMPHIS, TN
Dec 16, 2012 6:15 PM Arrived at FedEx location NEWARK, NJ
Current estimated delivery Tues Dec 18, 2012 by 10:30 AM BROOKLYN, NY
As far as I can see, the only odd thing about my story is my iMac got a direct flight from Shanghai to Memphis, then spent Saturday in Memphis (presumably listening to music). So remember "business days" means the process slows down over the weekend. Oh, and I told my wife what I'd done tonight, and note: was still alive to make this posting!