Originally Posted by Hhonor Gguard

Online check-in does not actually register you as a guest, it merely assigns you a room and expedites the check-in process. By all means, use OLCI but CALL THE HOTEL and tell them to check you in on the 24th so the room is already registered to you for the morning of the 25th. This way the room is processed during the 24th's night audit and is transmitted to HHonors for credit.