score:6
The Christmas market is right in the center of the city at the Kurhaus (Collonades). https://visit.baden-baden.de/en/events/baden-baden-christmas-market . There are plenty of hotels within easy walking distance.
As the comment mentioned, the main action starts late afternoon/early evening when it's getting dark, since the illuminations are a lot more fun and most people are done with work (on non-weekends). While it officially opens at 11am, it will be pretty quiet that early especially on weekdays.