can anyone tell me what is the earliest we can be at the gate in order to be sure to get a table for 4th of July? what time do they open? or can we make a picnic reservation??

You can make a reservation for certain specific areas there. Some of the areas are by reservation and some of the areas are not. Me and my people went there last Saturday and it was reserved but we had to reserve from 10:00 to 2:00 or 2:00 to 6:00. But like I said there's other picnic areas that don't have to be reserved at all. I sure would call well in advance if I were you and get the information from the horse's mouth... If you really want to get that table for the 4th!

Like Elizabeth said, you can park on the street and just walk in and have someone wait there at a table that isn't reserved. That's probably your best.

12pm

You can always park on the street side and walk up to a picnic table.