You'll need to decide where you are going to park, general parking means you have to get the tram from the parking lot to the Transportation and Ticket Center, the TTC is where the Ferry is and Monorails are. If the monorail is running, you can take that to Magic Kingdom entrance. If the ferry is running, you can do that instead if you want.
If you want to get closer, you can pay for Valet parking at the Contemporary Resort, and then take the walking path from there to the front of Magic Kingdom, could take 15-20 minutes to get to the front. Or you can take the monorail from inside the resort if it is running.
Once you get into MK using your early ADR, head towards the castle, walk until you get to Cinderella's Royal Table entrance located in the castle.