The high class client is random, but on a 45 minute shift I normally get one. Was lucky a few times and got one right at the start. If you get one, focus on him until he runs out of money.
Fast fill worked very well for me, it balanced it even if I had wine or beer left. Could have been luck, but with older versions of the game I often got 6 wine bottles (or only beer), so I think something has changed.