Show custom message in WooCommerce checkout based on shipping country

I'm currently using the code below to show a custom message based on country:

add_action( 'woocommerce_before_checkout_billing_form', 'display_shipping_notice' );
function display_shipping_notice() {
    echo '<div class="shipping-notice woocommerce-info"  style="display:none">Please allow 5-10 business days for delivery after order processing.</div>';
}
  
add_action( 'woocommerce_after_checkout_form', 'show_shipping_notice_js' );
function show_shipping_notice_js(){
    ?>
    <script>
        jQuery(document).ready(function($){
            // Set the country code (That will display the message)
            var countryCode = 'GB';
  
            $('select#billing_country').change(function(){
                selectedCountry = $('select#billing_country').val();
                  
                if( selectedCountry == countryCode ){
                    $('.shipping-notice').show();
                }
                else {
                    $('.shipping-notice').hide();
                }
            });
        });
    </script>
    <?php 
}

The problem with this code is that it will only show the message if the country is changed or selected. However, most customers already have their country pre-filled, so the custom message will not show.

I'm trying to find a way to alter the code to make the message always show when the correct country is selected.

I have revisited your code, changing:

• the success message (blue) to a notice message (green),
• the JQuery code to handle the country on load when DOM is loaded.

But note that your jQuery code is handling Billing country (see at the end for shipping country).

Try the following instead:

add_action( 'woocommerce_checkout_before_customer_details', 'display_shipping_notice' );
function display_shipping_notice() {
    echo '<div class="shipping-notice woocommerce-message" role="alert" style="display:none">Please allow 5-10 business days for delivery after order processing.</div>';
}

add_action( 'woocommerce_after_checkout_form', 'show_shipping_notice_js' );
function show_shipping_notice_js(){
    ?>
    <script>
        jQuery(function($){
            var countryCode  = 'GB', // Set the country code (That will display the message)
                countryField = 'select#billing_country'; // The Field selector to target
            
            function showHideShippingNotice( countryCode, countryField ){
                if( $(countryField).val() === countryCode ){
                    $('.shipping-notice').show();
                }
                else {
                    $('.shipping-notice').hide();
                }
            }

            // On Ready (after DOM is loaded)
            showHideShippingNotice( countryCode, countryField );

            // On billing country change (Live event)
            $('form.checkout').on('change', countryField, function() {
                showHideShippingNotice( countryCode, countryField );
            });
        });
    </script>
    <?php
}

Code goes in functions.php file of the active child theme (or active theme). Tested and works.

Caution: If you want to handle the shipping country instead of billing country, replace:

                countryField = 'select#billing_country'; // The Field selector to target

with this:

                countryField = 'select#shipping_country'; // The Field selector to target

Now It will handle Shipping country.