Yes, you can prep this recipe ahead of time! Just prepare the recipe as-written, up to the point where you will start the 15 minute soak. Rather than letting the bread pudding soak on the counter for 15 minutes, cover the bowl and place it in the fridge for several hours or overnight. When you want to bake the pudding, remove the bowl from the fridge and let it sit out while the oven preheats. Give the mixture a final stir and then bake as instructed in the recipe.