<script type="text/javascript" charset="utf-8">
 
  // Delay time in seconds
  var delayTime = 20;
 
  $(document).on('ready pjax:scriptcomplete',function(){
    $('#ls-button-submit').prop('disabled', true);
    setTimeout(function() {
      $('#ls-button-submit').prop('disabled', false);
    }, delayTime*1000);
  });
</script>

<div>The "next" button <span id="timer1">will be enabled in 10 <span> seconds. </span></span></div>
<script>
   window.onload = function(){
     var sec = 9;
     setInterval(function(){
 
       document.getElementById("timer1").innerHTML = "will be enabled in " +sec +" seconds.";
       sec--;
       if(sec < 0){
    document.getElementById("timer1").innerHTML = 'is now enabled.';
    }
      },1000);
    }
    </script>