A much simpler way to find out if the Apple Store next to you is loaded with iPhone 5s units is to head to iphone-check.herokuapp.com and plug in the zip code of the Apple Store you're interested in. Select from one of the three colors that the model comes in, the U.S. carrier you are interested in and you will soon have the coveted information right in front of you.
In case you're curious, the information comes straight from Apple, and the site shows the Apple Store's inventory regarding the iPhone 5s only. Referring to the chart while shopping for your iPhone 5s just might save you some time, something that you can never have enough of.
source: iphone-check, via Apple, CNET