To ensure the best results, it's important to keep your frosting sheet or cake topper in its original sealed bag until you're ready to use it. There's no need to refrigerate it, but be sure to keep it away from direct sunlight. When your birthday cake is ready, remove the topper from the bag and apply it to the cake. To prevent colors from fading, it's recommended to apply the topper within 24 hours of your event. For the most vibrant colors, apply the topper just an hour before serving.