We just came off a road trip where we stayed in 4 hotels in 4 nights. In 2 cases, we arrived before normal check in time. We arrived at 2:30pm at the first and 2pm at the second. In both cases, our room wasn't ready. In the second case, we weren't even asked our name. We were told that housekeeping hadn't prepared any rooms yet. In both cases, I was top tier elite but that was irrelevant to the desk agent. I think odds would be poor for a 6am check in.