I started doing this a few years ago to compare what my school district thought I should be teaching (and at what time) to what was actually happening in my classroom. It also become very useful to plan unit assessments with my PLC. You can use it for day-to-day planning, but it was intended for a broader visual of how to fit curriculum into the school year.
The calendar extends from August 1 to June 16. A sample of what I do with it is included in the preview thumbnails.
*Solid knowledge of formatting tables in Word is necessary to make any major changes.