Final answer:
The baker should spray a cookie sheet with a non-stick spray before rolling the cookie dough into balls.
Step-by-step explanation:
The baker should take the step of spraying a cookie sheet with a non-stick spray immediately before rolling the cookie dough into balls. This step ensures that the cookies do not stick to the sheet during baking, making it easier to remove them later. It also helps in promoting even browning and preventing the cookies from spreading too much.