A few days after I finished an online application, I got a call back from a manager at Panera. I scheduled an interview for later that week and wore just a button down shirt and some nice dress pants. My interviewer was very nice and went through exactly what I'd be doing at Panera, the way they'd train me (first basically busing, then the line, then cashiering, then possible barista) and if I were to get hired, how I'd have to go to two training meeting things. She also discussed how it was possible to move up and times they had reviews. It seemed to be going well and she covered the usual questions (why do you want to work here? what hours can you work? what are you most proud of? hobbies?) and made sure to let me know that she was going to have the head manager call me for another interview.
She kept her promise and called back the next day and I scheduled my second interview for two days later. I came a little less dressed to impress (I wore a polo and the same dress pants, probably not the wisest decision I've ever made) than the first interview and was somewhat distracted/derailed since I ran into a friend's ex boyfriend waiting to let the head manager I was there. He was very nice but I got pretty jittery and started talking with my hands a lot, so I wasn't surprised I didn't get the job. He said he'd call me Monday, and it's 11:32 PM on Monday night and still no call.
Edit: actually, I just got the job yesterday. Which was surprising, but I've accepted and now have orientation on Monday. So it's kind of weird how things worked out. I'm not really crazy that I had to wait ages to find out I got a job, especially since I have interviewed other places since then. But I am grateful that they did hire me. So, moral of the story: relax. You probably will do much better than you think.