You can check-in anytime and as mentioned they will give you keys and all the other information you normally get.
If a room is ready you'll get it. If not, you call later to find out what room was assigned.
As to getting into the room early or not, it all depends on a number of other factors. Here are my thoughts on what probably impacts room availability.
1. Was the resort full the previous night or were some rooms 'empty' and thus available immediately.
2. What day are you checking in? If it's a Sunday that's the heaviest check-in day of the week, so depending on what time of day you actually get there, any available rooms may already have been taken by people ahead of you.
3. What type of villa are you getting? Obviously the cleaning time varies considerably between a Studio and a Grand Villa. Thus certain types of rooms may not be available until later.
4. What people are checking out? Pure speculation on my part, but someone with an early flight may be checking out early and the room can be made available sooner. Whereas a large family in a 2-b/r may need to take the full 11:00 am checkout before they're ready to go. So if you're getting a Studio it might be possible it would be ready sooner than someone else getting a 2-b/r villa.
5. What type of 'requests' do you already have. Smoking-Non-Smoking is no longer an issue, but if you want ground floor, upper floor, a certain section of the resort, or a specific view, then these all affect the number of units that might be available earlier than others.
Just some thoughts....
Personal experiences, we've gotten rooms as early as 7:00 am, and as late as 6:00 pm. (meaning we were there by 4:00 but the room wasn't ready). The latest we've ever checked in was about 11:00 pm because that's when we finally got to the resort, and of course the room was ready....

, but, it was probably the least desirable location in the whole resort.