I never did it until my last trip, in November. I will do it again for this years trip. I got a text before I was even on DME, saying that my room was ready, with my room number and that I could go straight to my room if I wanted to. This was very convenient and knowing my room was ready before I even got to the resort was a relief. When my plane landed, I got a text that it was not quite ready yet, but then got another one after that. When you do online check-in, you can give your time of arrival - this is good, so they know when your expected arrival time is, I assume to try and get the room ready. It doesn't hurt to do online check-in. I also did NOT check the box off, that my room being ready took priority over my room requests.