Depends, it seems, on all kinds of unpredicatable factors. I've had beer carbed at a week (which was still green and crappy, incidentally), others that took four weeks. Couldn't begin to fathom why.
In any case, three weeks is better than two, there's a huge difference in the quality of the beer just by giving it a little more time to condition.
Come join Yankee Ingenuity!
"I'm kind of toasted. But I looked at my watch and it's only 6:30 so I can't stop drinking yet." - Yooper's Bob
"Brown eye finally recovered after the abuse it endured in Ptown last weekend, but it took almost a full week." - Paulie
"no, he just doesn't speak 'stupid'. i, however, am fluent...." - motobrewer
"... I'll go both ways." - Melana