I have time to mess around with gum paste and fondant this coming week and if something turns out ok I was wanting to use it for my sons cake...next month.

I was just wondering if that would be too far in advanced to keep and if not, how would you store either one for that long without something losing its shape?

TIA

@CalaMom ‍, as long as your figures, flowers or whatever are kept in a cool (not refrigerator, air conditioned room temp), dry place, gum paste, fondant or modeling chocolate will keep indefinitely.  If you are concerned about fading, you might want to keep your pieces in a low light area.

These items do have a shelf life. Those made with any chocolate will be shorter due to the nature of chocolate going rancid. I keep my buckets of fondant, gum paste, and modeling chocolate in the fridge or freezer, since I order in advance and typically use a white chocolate fondant (Choco-pan or Dream Fondant). Whatever you model in advance, you should keep in Tupperware (I mean the real stuff with a round seal that actually keeps air out) until you are ready to use to keep it from getting too dry. If it is gum paste, you definitely want to keep it sealed up to avoid getting exposed to humidity - so it doesn't go limp. 

I've made gumpaste figures a month in advance and I have had no issues. This is using satin ice gumpaste not gumpaste made from fondant with tylose. My new favorite fondant recipe has white chocolate in it so if I added tylose to that and then made figures I don't know if I'd do it a whole month in advance.

I made some simple gumpaste flowers probably a year ago from satin ice and they still look perfectly fine. Not sure how they'd taste but I don't think they'd have tasted great at any point after drying fully ...

I've heard it's better to keep them in a cardboard box to prevent them from getting dusty, rather than a plastic tub that lets no air at all in .. but I'm not sure on how "true" that is....

I have figures made of modeling chocolate, flowers made of gum paste and dummy cakes made of fondant that are years old and they have not changed at all.  I would never seal them in an air tight container, but as @Coffeelover77 ‍ said, they do need to be covered to prevent getting dusty.  Of course, none of these pieces were ever intended for consumption.

I keep my (homemade Nicholas Lodge's recipe) gum paste double wrapped in cling wrap and sealed in a zip lock bag in the refrigerator and both fondant (homemade Liz Marek's LMF) and modeling chocolate (homemade Shawna McGreevy's recipe) sealed the same and left at room temperature.  Perhaps because I use Candy Melts to make modeling chocolate, I have never had it turn rancid.

As long as they are kept away from heat & light they should be fine for you purpose.   Many, many gp flowers can be purchased ready made.   Do you really think they were made just the day before they were shipped out?   I also have made gp flowers probably as much as a month ahead w/o any problems - stored lightly covered w/plastic wrap or in a cake box.