There is an option for Graphics such as DateListPlot called Ticks. Ticks allows you to specify what the tick marks of the graph should say. For example, if I want the ticks to be the months of the year, I might write something like:

monthTicks = 
  Transpose[{Table[
     QuantityMagnitude[
      DateObject[{2014, i, 1}] - DateObject[{2014, 1, 1}]], {i, 1, 
      12}], {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", 
     "Sep", "Oct", "Nov", "Dec"}}];

DateListPlot[ ... , Ticks -> {monthticks, Automatic}]