Most hair coloring experts advise waiting a few weeks between dye applications, because newly colored hair needs time to dry and air out. The length of time between hair dyes varies for each person, however.
After dyeing, it should probably not be dyed again for quite some time. It all depends on the condition of the hair. A hair stylist is the best consultant on this matter, because she knows when the hair is ready to dye again. If the hair is damaged, it is best to wait until the hair is in better condition to ensure the best coloring possible.