Date formate on Booking Form

You can add the javascript code below to the page using Per Page Code Injection. 

Javascript

(function(){
  if (document.readyState == 'loading') {
    document.addEventListener('DOMContentLoaded', init);
  } else {
    init();
  }
  function init() {
    var dayField = document.querySelector('.date .day');
    dayField.parentNode.insertBefore(dayField, dayField.previousElementSibling);
  }
})();

Make sure you add the code between <script> tags, e.g.

<script>
  // JS code goes here
</script>