Add delivery date and time for woocommerce

/**
 * Add the field to the checkout
 * */
add_action('woocommerce_after_checkout_billing_form', 'my_custom_checkout_field');

function my_custom_checkout_field($checkout) {

    echo '
' . __('Prefered delivery time', 'woothemes') . '
';
    
    $tomorrow = date('Y-m-d', strtotime(the_date('Y-m-d', '','', FALSE) .' +1 day'));
    $after_tomorrow = date('Y-m-d', strtotime(the_date('Y-m-d', '','', FALSE) .' +2 day'));
    $_3day_now = date('Y-m-d', strtotime(the_date('Y-m-d','','', FALSE) .' +3 day'));
    echo '
';
    woocommerce_form_field('prefered_delivery_date', array(
        'type' => 'select',
        'class' => array('form-row-first form-row-wide'),
        'label' => '',
        'options' => array(
            $tomorrow => $tomorrow,
            $after_tomorrow => $after_tomorrow,
            $_3day_now => $_3day_now
         )
            ), $checkout->get_value('prefered_delivery_date'));
    echo '
';
    woocommerce_form_field('prefered_delivery_time', array(
        'type' => 'select',
        'class' => array('form-row-last form-row-wide'),
        'label'   =>'',
        'options' => array(
            '9-12:00' => __('9-12:00', 'woothemes'),
            '12-15:00' => __('12-15:00', 'woothemes'),
            '15-18:00' => __('15-18:00', 'woothemes'),
        )
            ), $checkout->get_value('prefered_delivery_time'));
    echo '
';
    _e('
Orders placed after 6pm will not be processed until the next business day.
', 'woothemes');
    echo '
';
}

/**
  ?* Process the checkout
  ?* */
add_action('woocommerce_checkout_process', 'my_custom_checkout_field_process');

function my_custom_checkout_field_process() {
    global $woocommerce;
    if (!$_POST['prefered_delivery_time'])
        $woocommerce->add_error(__('Please enter something into this new shiny field.', 'woothemes'));
}

/**
  ?* Update the order meta with field value
  ?* */
add_action('woocommerce_checkout_update_order_meta', 'my_custom_checkout_field_update_order_meta');

function my_custom_checkout_field_update_order_meta($order_id) {
    if ($_POST['prefered_delivery_date']) update_post_meta($order_id, 'Prefered delivery date', esc_attr($_POST['prefered_delivery_date']));
    if ($_POST['prefered_delivery_time']) update_post_meta($order_id, 'Prefered delivery time', esc_attr($_POST['prefered_delivery_time']));
}

add_filter('manage_edit-shop_order_columns', 'set_custom_edit_shop_order_columns');
add_action('manage_shop_order_posts_custom_column', 'custom_shop_order_column', 10, 2);

function set_custom_edit_shop_order_columns($columns) {
    //unset($columns['date']);
    return $columns + array('delivery_time' => __('Delivery time', 'woothemes'));
}

function custom_shop_order_column($column, $post_id) {
    switch ($column) {
        case 'delivery_time':
            echo get_post_meta($post_id, 'Prefered delivery date', true)."
";
            echo get_post_meta($post_id, 'Prefered delivery time', true);
            break;
    }
}

add_action('woocommerce_admin_order_data_after_billing_address', 'add_delivery_order_data');

function add_delivery_order_data($checkout) {
    global $post;
    echo '
' . __('Custom prefered delivery time', 'woothemes') . '
';
    echo '
' . get_post_meta($post->ID, 'Prefered delivery date', true) .'
'. get_post_meta($post->ID, 'Prefered delivery time', true) . '
';
}