I hate to break it to you, but don't get your hopes up that the stout isn't still going to be green at Christmas, if even fully carbed.
The higher the grav or more complex the grainbill, the longer it's going to take both to carb and condition.
The
3 weeks at 70 degrees, that that we recommend is the
minimum time it takes for average gravity beers to carbonate and condition. Higher grav beers take longer. As do beers with more complex grain bills, like with darker grains.
Stouts and porters have taken me between 6 and 8 weeks to carb up and come into their own.
I've written about the process here.
Of Patience and Bottle Conditioning.
I mean you can bottle it now, but there's really no gaurentee, and in my experience, the odds are against it not being green in 3 weeks. Of course you could always see if it's any better on New years.
Like I said I hate to be a downer, but when I am planning to have something done by a certain date, I try to have a minimum of 4 weeks in the bottle before hand. And even then that much is cutting it a little close, and I'll have a backup plan.
For Example last year, I brewed my Pumpkin Ale for Thanksgiving on Labor Day...figuring at 8 weeks, I MIGHT have some ready for Holloween...But they were still green, so I only brought a couple to my annual Halloween thingy, along with a sampler of commercial pumpkins...BUT come Turkey Day the beer was fantastic, and was a hit at the holiday.
This year with my mother in the hospital most of the summer, I wasn't able to brew as much as I wanted, and knowing that I wouldn't be able to have a good Pumpkin in the fall, I skipped brewing one.
Rather than forcing something into your timeframe, and being dissapointed, I would leave it in primary for a couple more weeks, then bottle, and let it go. And drink some nice commercial stouts at Christmas instead.
Personally I would rather make a good beer, than a fast one. But that's my take on it. I'm only saying it so come Christmas if it's not to your liking or carbed, you won't be too dissapointed.
