Next Sunday is kind of vague...
This Sunday 6/29 or Next Sunday 7/6/2014...
If 7/6 consider bringing that coke can for an hour early entry into the park.
https://www.sixflags.com/greatadventure/special-events/celebration/july-4th-fest
Also consider staying for the firework...If it is still Pyrotechnico doing the show it will be well worth the stay.