The gougères can be made up to 1 day ahead and stored in an airtight container. Rewarm in a 350° oven before serving.
If you use two different kinds of baking sheets when making this recipe, check that the gougeres bake at the same rate. To help achieve even baking, consider investing in a pair of Silpats, reusable silicone pan liners. They are available in most kitchen stores, like Sur La Table.