Once the dough is on the cookie sheet, it's ready to bake. Preheat oven to 375 and bake for 5 minutes then turn 180 degrees and bake another 5 minutes. Don't be alarmed if the dough is still pasty white at the end of the baking. As a frequent chocolate chip cookie baker but first time sugar-cookie baker I ruined my first batch by letting them cook until they were browned. Also, the more you bake the cookies the more stiff, crumbly, and difficult to cut they become. The bottom edge should be just beginning to turn golden when the cookie comes out.
Once the dough is out of the oven, carefully use the parchment to slide the dough off onto a clear flat space where it can rest and cool while you start your next sheet of dough baking.