For those facing disable previous time from dateA - dateB which dateB cannot greater than dateA. I would like to share my code here to help :)
    var calImg = '@Url.Content("~/Images/ico_calendar.gif")';
    var dtFormat = 'd-M-yy';
    var showType = "button";
    var dates = $("#newsDateFrom, #newsDateTo").datepicker({
        dateFormat: dtFormat,
        showOn: showType,
        buttonImage: calImg,
        buttonImageOnly: true,
        numberOfMonths: 3,
        onSelect: function (selectedDate) {
            var option = this.id == "newsDateFrom" ? "minDate" : "maxDate",
 instance = $(this).data("datepicker"),
 date = $.datepicker.parseDate(
  instance.settings.dateFormat ||
  $.datepicker._defaults.dateFormat,
  selectedDate, instance.settings);
            dates.not(this).datepicker("option", option, date);
        }
    });
 
    