It really isn't any different than chopping vegetables in the AM to add to a soup in the evening.
I often mix up the dry ingredients for pancakes or muffins the night before. In the morning I just add a few items, mix and go.
I also sometimes mix the dry ingredients for something I want to make in the evening while dinner is cooking (i.e. if something has to simmer for 15 minutes or if everything is ready but DH won't be home for another 10 minutes). Just efficient use of your time!
Less rhetoric, more cowbell!