Christian,
What you can expect is a fun and relaxing day in the park.
I would suggest arriving about 9:30 or so (allow about 2 hrs from the SW suburbs if you're coming to Eureka, plus a little extra if you want to wash the car when you get to town). When you get to the event, you'll park with the rest of the SQ competitors and that is where your car will stay for most of the judging process. In-place judging allows you to leave all your stuff in one place and open the car for display most of the day. The only time you'll need to move is to get your spl measured and then you'll return to your spot.
During the install judging, you will get 5 minutes to present your car to the judge. Basically what you want to cover is what you did to make sure your install is as solid as it could be. Sell the integrity of the installation, because under the Street rules format this is the most important thing. Other high points are safety of the install (proper wire size, fusing, grommets and terminations) and safety of the vehicle (no modifications to OE airbags, seatbelts, seat position, vehicle controls). The typical approach is to start under the hood at the battery, then go to the rear of the vehicle to show the trunk and then finally to the interior of the car. But everyone has their own variations of this.
2 major points of consideration: Make sure the main system fuse under the hood is no more than 18 inches from the battery and make sure there is a grommet where the power wire passes through the fire wall.
Pictures will be beneficial if there is any aspect of the install's integrity or safety you want the judges to know about, but cannot show them unless you have the picture. One example would be the fuse for the head unit.
Let me know if you have any additional questions.
