ok, let me clarify my question...

So, you have a lot of wonderful sites/programs that let you choose color palettes (i am using Kuler), and you (you, not me ) are expert in color theory.
So, you start working... and sure you use colors, after or before!

But: "when" you choose your color scheme? In the planning phase, or after? How do you avoid to go halfway only to discover that your palette is not the "right one" for your map?
Do you use maybe a small sample from the map for practice, or rely on old tested schemes? It is not simple to revert to another palette, if something goes wrong...

It is more a metodological than a strictly practical question, and i know everyone probably use his own method, and surely experience plays a great role letting you to figure the result in advance: but i was interested in some practical examples or advices from you fellow mapmakers, since i am working to improve my ability.