Good for you to be thinking ahead. Your score is just one consideration, having a good pay history in the past 1-2 years, your income, debt load, job time, down payment are a few others. While January seems like a long time off, I'd really encourage you to meet with a local mortgage lender now and let them know about your intentions.
By applying early and obtaining a valid copy of your credit report you can see if there are issues you can address there to improve your chances of success. As a lender, I have assisted several people work through credit issues and help put them on the right path to purchase.