pauloL

the Wordfence Security can delete it?

I do not quite understand. You want dates before checkin stay locked?
See this example:
http://jsfiddle.net/LLY3g/

Create inputs with id checkin and checkout:
Exemplo contact form 7:
[text date-go id:checkin]
[text date-back id:checkout]

Put it in the functions.php file:

add_action('wp_head', 'ativa_data');
function ativa_data(){
?>
	<script type="text/javascript">
		jQuery(function() {
			jQuery("#checkin").datepicker({
				dateFormat: 'yy/mm/dd',
				minDate: new Date(),
				onSelect: function() {
					jQuery("#checkout").datepicker('option','minDate',jQuery("#checkin").datepicker( "getDate" ));
				}
			});
			jQuery("#checkout").datepicker({
				dateFormat: 'yy/mm/dd',
				minDate: new Date()
			});
		});
    </script>
<?php
}