True, cookies should come out when they are slightly underdone because they will keep baking for another couple of minutes. However, I hate cookies that are still slightly raw in the center. I usually check the bottom of one cookie by gently lifting it using a spatula. If it is golden brown then I know it's time to take them out of the oven. If you see the edges just starting to brown that's also a good time to take them out and let them cool.