I've done several of these shops.
One thing you can do is call and say that your co-worker, friend, sister, etc just had her makeup done there by a NARS artist and you liked it so much that you want to do it as well. Can you tell me who that is so I can look for him/her or make an appointment?
I find these shops fairly fun and easy and I almost always learn something new.
Hope this helps.
Heather