Get all the documentation you can when you notify them that you will not be there till the next morning.
I booked a room at the Crowne Plaza Gurgaon (India) and told them I was arriving at 11 PM so they wouldn't give the room away. When I arrived, tired and grungy from the ORD-DEL nonstop, my room wasn't ready. Since many international flights from DEL leave at night, my guess was that they let someone stay in "my" room past checkout time (for a fee, of course), and then didn't get it cleaned up and prepared in time for my arrival. I spent an unhappy hour in the lounge waiting for my room to be ready. Since I was heading into the office bright and early the next AM, I didn't appreciate it.