There are three methods that can be used to tell GeneHunter when to stop evolving.  You can start with the default selection, and later change to something else if you feel it is more appropriate.

Time Elapsed - This method allows you to specify that evolution should stop after a certain number of minutes.

Generations Greater Than - This selection will cause GeneHunter to stop after the number of generations has exceeded a certain number. After you have run a particular problem a few times, you will probably find an appropriate number beyond which the GA seems to make little progress.  This number might be an appropriate upper limit.

Best Fitness Unchanged After... - This selection, which is the default, is normally the best selection.  If, after some number of generations, a better fitness value has not been found, then it is probably appropriate to stop.  How many generations is a good number to wait?  There is no number that fits all problems, but generally, if nothing has happened after 50 generations, it is time to stop.