Modify backorder message (single product and cart )

Paste the following code in functions.php:

/* backorder text on single product page */
function so_42345940_backorder_message( $text, $product ){
  if ( $product->managing_stock() && $product->is_on_backorder( 1 ) ) {
      $text = __( 'Please allow 20 days for delivery of this item', 'your-textdomain' );
  }
  return $text;
}
add_filter( 'woocommerce_get_availability_text', 'so_42345940_backorder_message', 10, 2 );

/* Backorder text on cart page */
function alt_message() {
  return '

Please allow 20 days for delivery of this item

‘; } function backorder_text($availability) { $altmessage = alt_message(); foreach($availability as $i) { $availability = str_replace(‘Available on backorder’, $altmessage, $availability); } return $availability; } add_filter(‘woocommerce_get_availability’, ‘backorder_text’); function woocommerce_custom_cart_item_name( $_product_title, $cart_item, $cart_item_key ) { $altmessage = alt_message(); if ( $cart_item[‘data’]->backorders_require_notification() && $cart_item[‘data’]->is_on_backorder( $cart_item[‘quantity’] ) ) { $_product_title .= __( ‘ – ‘. $altmessage, ‘woocommerce’ ) ; } return $_product_title; } add_filter( ‘woocommerce_cart_item_name’, ‘woocommerce_custom_cart_item_name’, 10, 3);

Paste the following in Appearance > Customise > Additional CSS:

.backorder_notification{
    display: none;
}
.backorder_notification_custom{
    display: block;
    margin-bottom:0px;
}

Source: https://www.choosepizzi.net/woocommerce-modify-backorder-message-single-product-and-cart/