If you don't click a date and click book a room it doesn't pull through

Hello,

When someone using the book a room bar on this site (on the homepage its below the image at the top of the page) if you don't click a date and click book a room button and then one you get to the next page and try to pop in a date it comes up with an error message.

But if you still click todays date and book it pulls through.
I feel like i need some code of something which pulls though the current date even if no date is clicked on.

Please see the attached php for the bar and please follow the url to video a video to show what I mean. https://monosnap.com/file/6n5A5Wq3dj4sBfsVw9GCi9CBrJvrSg

<?php

    $forts = [
        'nomans'   => [
            'id' => 'NOMANS',
            'name' => 'No Man\'s Fort'
        ],
        'spitbank' => [
            'id' => 'SPITBANK',
            'name' => 'Spitbank Fort'
        ]
    ];
?>

<section class="c-booking-bar / js-bookingbar">

    <div class="c-booking-bar__slab">

        <div class="row">

            <div class="columns">

                <form action="<?php echo get_field('synxis_base_url', 'option') ?>" method="get" class="c-booking-bar__form">

                    <p class="c-booking-bar__wide">
                        <label for="hotel-selection"><?php _e('Fort','creative'); ?><span class="screen-reader-text"> selection</span></label>
                        <select name="hotel" id="hotel-selection">
                            <?php foreach ($forts as $fort_slug => $fort_details):

                                /**
                                 * Auto select the fort based on the main-navigation selection
                                 */
                                $navigation_selection = cn_recursive_field('navigation_selection');

                                if ( $fort_slug === $navigation_selection ) {
                                    $selected = 'selected';
                                } else {
                                    $selected = '';
                                }
                            ?>
                                <option value="<?php echo $fort_details['id'] ?>"<?php if( !empty( $selected ) ) { echo 'selected="' . $selected . '"'; } ?>><?php echo $fort_details['name'] ?></option>
                            <?php endforeach ?>
                        </select>
                    </p>

                    <p class="c-booking-bar__wide">
                        <label for="arrive"><?php _e('Check-in','arrival'); ?></label>
                        <input type="text" name="arrival"  id="arrive" class="js-datepicker" placeholder="<?php echo date('jS F, Y') ?>">
                    </p>

                    <!-- <p class="c-booking-bar__wide / hide-for-medium">
                        <label for="depart"><?php _e('Check-out','creative'); ?></label>
                        <input type="text" name="depart" id="depart" class="js-datepicker" placeholder="<?php echo date('jS F, Y', strtotime('+1 day')) ?>">
                    </p> -->

                   <!--  <p class="c-booking-bar__thin / hide-for-medium">
                        <label for="rooms"><?php _e('Rooms','creative'); ?></label>
                        <input type="number" name="rooms" id="rooms" placeholder="1" novalidate autocorrect="off" pattern="\d+" min="1" max="15">
                    </p> -->

                    <p class="c-booking-bar__thin / hide-for-medium">
                        <label for="adult"><?php _e('Adults','creative'); ?></label>
                        <input type="number" name="adults" id="adult" placeholder="1" novalidate autocorrect="off" pattern="\d+" min="1" max="15">
                    </p>

                    <p class="c-booking-bar__button">
                        <button id="c-booking-bar-button" class="c-book-button" type="submit"><?php _e('Book a room','creative'); ?></button>
                    </p>

                </form>

            </div>

        </div>

    </div>

</section>