I am making a cake for my sister with molded fondant pieces on it. I am wondering how far in advanced I can start molding? I am thinking of just putting them in ziploc bags do keep them pliable. Any suggestions?

I worked for a very high end bakery a few years ago and we made dozens of sea shell cakes. We sometimes took an entire day just making shells from fondant. We then stored them in shirt boxes (Yep, the kind you'd gift wrap!!) and wrote on the ends what type of shell was inside. I think if you want them pliable, you'd better wait until the last minute! Fondant dries out very quickly. Hope this helped.