The Office actress accepted writer Kirk's marriage proposal during a European vacation in June (09).
Now the planning of the nuptials is in full swing, and Fischer admits it's harder work than she ever imagined.
She tells Us Weeky, "Suddenly I care very much about all of these things I didn't think I would. I spent three hours at the invitation store."
Fisher, 35, divorced her first husband James Gunn in 2007.