We have done this on two different trips. I called and had it noted on the reservation and then I also made sure that I called on the listed check in date. The only problem we had was that the first time they tried to tell us that we had to wait until 4:00 check in time for our room on the later arrival day, but we said NO WAY, that room was officially ours since the day before and it would not be right if they had "double dipped" - taken money from someone else for the room we already paid for. The second time we did it, I just said that we would be checking in sometime the second day with the possibility of a middle of the night arrival on the official checkin day like 4 or 5 am. No comments were made the second time.