Only take the January MCAT if you have something that will keep you from studying during the Spring semester. If you don't have a good excuse to take it in January, then study through the spring semester and give yourself the chance at a higher score than if you were to take it in January. Getting your scores back in February does you no good, since they will sit idle for 4 months before applying. Go for the April MCAT, it sets you up for getting scores back in May, which is exactly when you should be applying.
EDIT: On the other hand, take it in January if you feel like you could never be more ready in your entire life. But that makes it a last minute call.