code: public static Day getFirstOfMonth(int dayOfWeek, int month, int year)
    {
      return Day.getNthOfMonth(1, dayOfWeek, month, year);
    }
docs: Find the first of a specific day in a given month. For instance
  first Tuesday of May:
  getFirstOfMonth(Calendar.TUESDAY, Calendar.MAY, 2005);
  
  @param dayOfWeek  Weekday to get.
  @param month      Month of day to get.
  @param year       Year of day to get.
  @return           The requested day.