Probably better to wait at least a few weeks rather than take the test if you "don't feel ready at all." Just remember to reschedule at least 7 days before the test so that you do not have to forfeit the full $250. The fee to change is $50 if you reschedule at least a week before the test.
Also remember that you can only retake the test every 31 days. I like the idea of not waiting to put all of your plans on just one test administration. Perhaps you could reschedule to sometime in early November and have an additional 6 weeks to study, plus a chance to take the test a second time if needed. You would have another 31 days of studying between the two tests if needed.
Also, I am not sure why early December would be too late for a January application deadline. Will you be determining which schools to apply to based on your GMAT score? If so, then December would certainly be too late. If you are already working on your applications then you should be fine.
I have not known too many people have success at a GMAT test date if they did not feel ready and were not close to their goal score.
We can give you additional advice about why your score is where it is if can provide some details - why do you think it might be the timer? Do you rush? Are you doing better on official questions on paper - like OG12?
Good luck with whatever you decide!
David
