I often plan in the evening. For example, I might make a list of things to do the next day, or rewrite my plan of action for finishing a project. These planning sessions do not produce any actual writing, but I find they are tremendously productive.
I like writing and rewriting my plan of when I will write what chapters. It keeps me on track and motivated, and allows me to see my weekly, monthly, and yearly goals with great clarity. If you have a very mild form of obsessive-compulsive disorder, as I do, it can be very reassuring.