Hello, Vitamin C, to be effective, should make and use very soon because if not, it can lose its effectiveness. Is it true? When should I use Vitamin C? AM or PM? I have found this https://www.sr-skincare.uk/product/vitamin-c-serum-with-ferulic-acid-and-vitamin-e/ Do you think it is effective enough? Many thanks for your time, Have a wonderful day.