The parking lot opens an hour before official opening time. If regular park opening is at 9 am (extra early hours start at 8:30) - parking lot opens at 8. You actually will loose your 30 minutes by driving to MK. Once you park at the Ticket and Transportation Center, you need to catch the parking lot tram or walk and then catch the monorail or boat to the MK entrance. Note, that the parking lot is open to all guests an hour before park opening. You will be in the mix of regular guests (regular opening time) to get to the park. There is no way, to separate when driving to MK.