Use the German rail website http://www.bahn.de/i/view/GBR/en/index.shtml for train schedules. Even though this site is in English, you may have to use the German names, the autofill function will help you. Take into account the time you need to get to and from the train stations to your hotels (you won't want to carry luggage around while you're sightseeing), and the time for packing, unpacking, checking in and out. That will tell you how much time you'll have to spend in each place you stop.
If there are no schedules for your dates yet, use the same days of the week, just earlier. Schedules will probably be the same.