With my first two children I made them up every 24 hours but I didnt keep them in the fridge, I kept them on the kitchen side or in the cupboard at room temperature when bubba wanted a bottle I just grabbed it and fed, I know they advise to put in the fridge but I never did and my kids are fine, I'll do the same with this one aswell
When you are at the hospital the milk they supply are not kept in the fridge or the cartons in the supermarkets, I understand they may have a preservative or something in them, saying that I expressed with my second and will be for this baby and would keep this in the fridge