Every year I make the decision somewhere around October 31st. I usually decide for NaNo in hopes that the competitive nature and supportive community will help me to break through what appears now to be an annual lull in creativity. I'm not sure what it is about October that stalls my writing, but I'm starting to think it can't be a coincidence.
This year I have added stress from household issues, and nothing kills creativity like a boatload of stress. However, I have previously found that writing can also be an escape. I don't get much actual writing done whilst in the middle of editing, so if I'm to find that magical escape, I'll have to shelve the mainstream novel again for awhile.
Methinks I will try NaNo again this year and see if I can jump start my creativity by working on something new. If nothing new comes to me, then I'll go rebel and work on my mystery novel, which is this year's official project.
Who knows? Maybe NaNo will help me come up with my next novel idea, so to speak.