Remembering Krispy Kreme's entrance to the market, I doubt 11:30am will avoid the crowds. I would think more like 10pm would do it.

I like Sonic, but I can't wait a half hour for a parking spot.
Unfortunately, I'm not going to be available on a weekend until sometime in October. Fortunately, I'll be in Phoenix and Nashville much of that time, and can therefore continue to get my monthly Sonic fix.
I could probably do Labor Day itself, however.