How early can you arrive at Rubble Creek Parking lot?

I'm planning to hike Panorama Ridge as a day hike on Saturday. I'd like to get started early, around 6:00 a.m. or so, so I'm not rushed. Will I be able to get into the parking lot that early? If I arrive before they have park staff checking parking passes will I end up getting a ticket? The pass doesn't have hours on it and I can't find any info on the website. Thank you!