Add warning on top of estimated delivery date

functions.php

add_filter( 'xa_estimated_delivery_cart_checkout_page_html_formatted_date', 'ph_estimated_delivery_add_warning_on_above_estimated_delivery',11,2 );
function ph_estimated_delivery_add_warning_on_above_estimated_delivery( $text, $test  ) {
    $message='<tr class="shipping"><th>Your cart having back-order products</th></tr>';   // add your message here
   	$text=$message.$text;
    return $text;
}