I'm in kind of a similar situation where I was originally studying to take FAR in November, but because of work and other miscellaneous didn't get around to all of the sections. I've been studying the last week or so to take the exam on 1/4 and have just gotten through all of the sections that I didn't get around to the first time and am starting to review those that I did. What I'm finding is that despite not having looked at those areas in over 6+ weeks, I've actually retained quite a bit and am scoring decently on the progress exams (75%-80%) because they were topics that I was previously more familiar with (revenue recognition, accrual basis, inventory etc.)
With that being said, if you have the time to start studying now, I'd definitely go through the sections that you're more comfortable with because, chances are, a brief refresher now will stick with you and help even a few weeks down the road. Save those topics that you are more unfamiliar / uncomfortable with for when you're closer to your exam date so you don't just forget completely over the weeks. Then the week before / week of your exam, read through those sections that you're the most comfortable with / do any MCQs that you may have marked as important and focus the majority of your review on those sections that you've identified as key / are still uncomfortable with.
REG - 7/2/12 - 89
BEC - 7/9/12 - 91
AUD - 5/13/13 - 87
FAR - 1/3/14 - 80
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