If you're scheduled to be at OCS during Christmas (they've scheduled a holiday stand down from 18DEC through the New Year), what are the chances the staff will make you stay behind? In other words, if you don't have the leave earned yet (obviously) or say the staff has some other reason (your fat, dumb, or both), has anyone heard of the staff denying leave and assigning monkey work until training resumes in January?
Your leave will not be denied. If you haven't yet earned any leave, you will simply go in the hole (negative leave balance). It's no big deal.