You can download and customize the calendar for your school.
I usually print out several grayscale copies to mark up as I figure out our school year and number the weeks.
Here are what all my markings mean:
The calendar helps me get a visual idea of how many weeks we really need to accomplish all of our goals and how many weeks we can use for breaks. I’ll add my final calendar to the Calendar page of my GGP Teacher Manual when it’s done.