Hi Payton! You can start whenever you want! As a 6th grader, you can start at home - helping with meals with your family, experimenting with new recipes, and watching professionals. Some community colleges over summer programs for kids where you can learn to cook or bake. You can also see if there are cooking classes in your community.
Once you get to high school, you may be able to take some electives in cooking or attend a vocational program that focuses on the culinary arts.