After months of waiting only 4 weeks left

I am finalizing my itinerary for the upcoming trip, and I would appreciate some suggestions. I have so many places I want to visit but unfortunately limited time. I will be traveling with my wife and 7 month old son. Landing in Munich Sunday morning and leaving the following Saturday. Plan on touring the sity on Sunday. Pickup car Monday morning and going to either Spitzingsee or Salzburg depending on Bimmerfest recommendations. What are the minimum number of days we would need in Salzburg? From Salzburg I was hoping to visit both Innsbruck and the castles near Fussen, but I don't think both will be possible. I was in Innsbruck in May once and day hiking was great, but not sure how Innsbruck will be this time of the year. Finally ending the adventure in Munich on Friday for droppoff, maybe visit Dachau before giving up the car.
Thanks in advance for any suggestions.