Too late for a Christmas stout

Should be ready by Halloween

 

ditto. Takes about 4 weeks to complete the process.

 

Agreed, you are early! Good planning!

 

You could brew mid November and have a beer ready for Christmas if you bottle condition and the first week of December if you force carbonate in a keg.

 

Going AG makes for a longer brew day, but does not extend the overall process. It's true that, as with extract, you need to think about a period of conditioning for many beer styles, but oatmeal stouts don't take anything out of the ordinary: a couple weeks ought to be fine. The thing you need to worry about in AG brewing this style is the possibility of a stuck sparge that you can get with oatmeal, so you might consider adding some rice hulls, just for insurance.