What I have heard is the free parking is only during the party. Not all day. But since you can enter DL at 3pm on Tuesdays and 4 pm on Fridays with your party ticket you can park at that time too.
The part which seems wierd is how do you arrive at the gate at 3pm on a Tuesday party day when you can't park for free until 3pm? It doesn't seem too convinient.
But the free parking is an enticement for locals to come to DL for the party, not to help people on multiday vacations or AP holders that come often already.
I've also wanted to find this out. It seems strange that if you can enter for the party at 3, you should be able to park before then.
We'll be there on the 11th also and I was hoping that someone who has done the party and was sure about the parking situation would let us know. I'd like to spend some time at WOD store before entering the park...