I've always heard it pronounced

Chick-fill-ay - rhymes with hooray!

Kay, I know you'll do fine, and it's great that you'll get to familiarize yourself with things first!

The key to dealing with customers is to smile a lot. And if you screw something up, say, "I'm sorry, it's my first day." If you say that with a smile, most people will immediately sympathize. You don't have to "mean" the smile, just seeinga smile will put people more at ease.