For an entry level position such as this, I would not even bother with a follow-up of the type that you’re thinking of – not at all. When people are being interviewed for these positions it’s because they are needed now. There isn’t the same lengthy hiring process that a professional would have to go through if they were hiring for, say, the store manager position. That one takes time to fill, and a lot of consideration of the various candidates’ good and bad points.
The position you want should be decided upon within a day of interviewing all of the various applicants. (There usually isn’t even a résumé requirement, just “fill out this application and talk to this person over here”.)
It would still be proper and courteous to send a thank-you letter, just because it is good manners, if for no other reason than that, but I wouldn’t bother with a follow-up call at all. Just go to your next best choice and go through their application process until you land the job you want.
Ideally, this is the kind of interview that you’ll have where the interviewer can shake your hand at the end and simply ask, “When can you start?” Aim for that job in this skill position. (Companies that are nimble enough to make those on-the-spot decisions are usually more enjoyable to work for, anyway.)