Call the hotel and tell them that you need the hotel starting on the morning of the day you want to check in, so you won’t be checking in until that morning, and not to cancel the reservation when you don’t check in the (first) night before. I do this all the time when I fly to Europe and want to access my room when I land in the morning.

If you actually won’t be there in the morning, call the hotel that morning and tell them you’ll be there later that day.