<?php
$name = get_user_meta( $customer_id, 'billing_first_name', true );
$nick = get_user_meta( $customer_id, 'nickname', true );
$username = strlen($name) ? $name : $nick ;
?>
<h5 class="smile">Добро пожаловать, <?= $username ?></h5>$(".order__plus").click(function () {
$(".order__input-number").val(+$(".order__input-number").val() + 1);
});