fullcalendar/locales/en-gb.js

FullCalendar.globalLocales.push(function () {
  'use strict';

  var enGb = {
    code: "en-gb",
    week: {
      dow: 1, // Monday is the first day of the week.
      doy: 4  // The week that contains Jan 4th is the first week of the year.
    }
  };

  return enGb;

}());