Is there a specific reason you want to take it in January as opposed to later? There really is no reason to try to rush your studying and preparation for the MCAT.
It is possible to jump 3 pts in that time, but it depends on why your scores are they way they are and how much time during that month and a half you're committed to studying. If you can identify certain "high-yield" areas where your score will improve if you bolstered up those areas, then it's a bit easier to increase your score. Also, if timing was an issue and you just need to take more practice tests to get the timing down, then that can help.