If you’re new to Medicare and would like to enroll in a Medicare Advantage plan, you can do so anytime during your Medicare Initial Enrollment Period. Your Initial Enrollment Period begins 3 months before your 65th birthday, includes your birthday month and ends 3 months after your 65th birthday. If you do not enroll in a Medicare Advantage plan during your initial enrollment period, you will have another chance to enroll during the Medicare Fall Open Enrollment Period, which runs from October 15 to December 7 each year.