I don’t recommend assembling the full cobbler until you are ready to bake it. However, you can make components ahead of time to make the assembly faster. Cook the filling, let it cool, and refrigerate it for up to 3 days. Just warm it back up on the stove or in the microwave when you’re ready to use it. You can mix the dry ingredients together several days in advance and stir in the milk and vanilla when you’re ready to assemble. Then, heat your oven and pan, pour in the batter, and dollop the filling on top.