One thing to note however is if you have a
DVC reservation where you check in after January 15 but before February 15, they will consider it late if paid after the check in date. Thus, you lose the 30 grace period.
ETA: I know I read this somewhere last year because I had a January 24 check in and made sure to pay my dues before check in just in case. However upon further research I can't find where I may have heard that. My inclination now is you're fine until February 15 regardless.