Just because you wanted it to be ready at 12 days doesn't mean it would be.
It's the standard response because it's 99.9% the right one, otherwise there wouldn't be a DAILY barrage of "It's been 2 weeks and my beer's not carbed" threads, would there be?
The
3 weeks at 70 degrees, that we recommend is the
minimum time it takes for
average gravity beers to carbonate and condition. Higher grav beers take longer.
Stouts and porters have taken me between 6 and 8 weeks to carb up..
I have a 1.090 Belgian strong that took three months to carb up.
Temp and gravity are the two factors that contribute to the time it takes to carb beer. But if a beer's not ready yet, or seems low carbed, and you added the right amount of sugar to it, then it's not stalled,
it's just not time yet.
Everything you need to know about carbing and conditioning, can be found here
Of Patience and Bottle Conditioning. With emphasis on the word,
"patience."
Lazy Llama came up with a handy dandy chart to determine how long something takes in brewing, whether it's fermentation, carbonation, bottle conditioning....
If a beer isn't carbed by "x number of weeks" you just have to give them more time. If you added your sugar, then the beer will carb up eventually, it's really a foolroof process. All beers will carb up eventually. A lot of new brewers think they have to "troubleshoot" a bottling issue, when there really is none, the beer knows how to carb itself. In fact if you run beersmiths carbing calculator, some lower grav beers don't even require additional sugar to reach their minimum level of carbonation.
We don't tell folks to wait because we want to torture new brewers and make them want to leave the hobby so there are less of them to compete against at contests and we want to be able to by their gear off craigslist dirt cheap. We tell them that, because that's how long it tends to take.
And all you have to do is see all those threads on here every week where folks complained about lack of carb and when you ask them how long the beer's been in the bottle they say it's been under three weeks. And if you follow up on those threads, usually the OP comes back after that period to announce their beer is carbed fine now....
Carbing is a natural process, it takes as long as it takes....and that's usually longer than we all want it to.