@mrcopilot @ramsey @stux if you are looking to see results right away, you can go with a tool like Game Guru MAX or Coppercube and have something within a few days.
Otherwise, its pretty impossible to answer depending on your learning capabilities, and how deep you are going into each facet. If for example you want to learn how to also create those trees/buildings, etc, that's a whole new set of topics to learn.