It's been hit or miss for us, too, but it does seem like doing online check-in (especially if we don't have a laundry list of requests!) increases our chances that the room will be ready early. Arriving on a weekday (instead of a weekend, when the cleaning staff is more taxed with rooms that need to be turned over for new occupants) also seems to help.
If it's not ready when we arrive, though, leaving our bags with Bell Services (and then calling to have them delivered after we arrive at our room later, following the text message with the room number - we do tip $1/bag when that happens) has proved to be very convenient. If you don't want to leave your bags in the car (vulnerable to heat and thieves) and would like the convenience of having them delivered to your door, definitely use Bell Services.