Assuming that you are not planning to ever eat your creations, you can do your Gingerbread and Fondant work way ahead of time; even two or more month ahead. In fact, for Gingerbread I suggest baking it weeks ahead and letting it dry out at room temperature to firm up and harden. Remember, we aren't making to to be eaten. I just protect it from dust and other unwanted elements. For Gum Paste and Fondant creations, these can be made many months in advance too. Once fully dried, I place these in an air tight container with bubble wrap in between for protection, as necessary. It really depends on your overall intentions but my general advice is that it is much better to start your project way ahead of time than to attempt to do a project sequentially shortly before an event or competition. This allows you to be more agile and gives you the opportunity to rework and re-do elements of a project, as necessary. Most of all, have fun!
Regards,
-Adam