Yes, you can prepare the strata on the same day if needed. Simply follow the recipe instructions, layering the ingredients in the baking dish. Instead of refrigerating overnight, let it sit at room temperature for about 30 minutes to allow the bread to soak up the custard mixture. Then, bake according to the recipe until the eggs are fully cooked and the top is golden brown. While the texture and flavor may not be as developed as when it's allowed to sit overnight, it will still be delicious and convenient for when you're short on time.