And you won't. The MCAT year runs from January to September each year, with no tests in February or from October through December.
January through June typically opens in October, and July through September usually opens in February. The month between December and January will be irrelevant to you with respect to an application next cycle.
The good news is that this year, due to all the COVID issues, AAMC will refund your money if you cancel before the deadline. There is normally a penalty that they are waiving this year, and fees never transfer between test years, so if you postponed from August to January in a regular year, you'd be out the $320, but not this year!!