I am making a farm cake for my son's 3rd birthday. this will be my first time making figures out of fondant/gumpaste and I would like to get a head start on them. I just don't know how far in advance I can make them, and how to store them until the big day.

You can make them a couple of weeks or more ahead of time. If you add some gumpaste or Tylose, they will set up a little faster. Just store them in cool, dry, dark place, like in a cabinet or pantry.