Let's remember that the first wheat that human consumed that was fairly late on the evolution timeline had only a small percent of the energy levels of the current wheat. Through engineering and selective breeding and other such methods, early humans managed to bring it to what we have now. So if we can increase the energy levels through GMO's, we can reduce those millions of years to hundreds of years.
Plus we only need to start to feed 10 people, then 50, then 200 and so on. It will grow with the colony. Nobody is going there hoping to start the terraforming on the next day :P