I just did both mine and my wifes and it was about 2 weeks from when I dropped the checks in the mail to when I got the new stickers. My wife's came a couple of days after mine.

As soon as the check clears they consider you legal, if just in their computer that every cop has. The sticker is just to keep you from getting pulled over if they're looking. Once they check you'll be ok.

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5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)