Last year you could enter after 4:00pm. They directed us to the turnstiles on the expo hall side and put wristbands on. After the 6:00 fireworks, they asked those with wristbands to go to Tomorrowland while they cleared the park. Rides in tomorrowland were still open but they checked for wristbands. As long as it's the same this year, you can plan for dinner in the park.