If you bake the dough balls immediately after they have been rolled, they will likely create a more spread & flatter version of the cookie. This is our preference. However for those who like a chunkier/thicker, more compact cookie, then place the dough balls in the refrigerator for about 20 minutes before baking to allow the dough to firm a little. This will help reduce the spread of the cookie.
The other consideration is whether you prefer a soft cookie or a firmer crunchier cookie. The longer you bake the cookie, the more firm it will become, so you are better to bake the cookie closer to the 15 minute mark (provided you will not burn them – depends on your oven).