They will gladly do it.... just takes time. I tell them at lunch if I want something, or as soon as the YC restaurant opens for dinner. And give them a heads up when you will be in for dinner. You are not getting it at 7:10 if you order at 7:05
They had a bunch, and even offered specials from time to time. My wife was excited, they offered Veuve. I'm not a sparkly guy, so not sure if there were nicer ones.