I believe the resort check-in counter opens at 5 AM. For a 10:10AM flight your bus would leave around 7AM, so I'm pretty sure you can check your bags at the resort.
I would use the resort check-in. It's very convenient and you're spared the hassle of checking in for the flight at the airport. We certainly loved it and had no problems when we used it.
Since you are not delivering your bags directly to the airline, just make sure the tags they put have the correct flight and destination info. You'll be fine.
Have fun!