How to determine if a customer is new in Magento when using afterSave (or other) Plugin?

Question

What is the best way to identify a new customer when using an afterSave Plugin?

Or should I use a different approach to do something with new customers?

Answer 1

Whenever a customer registered through the frontend form Magento trigger the customer_register_success event:

File: vendor/magento/module-customer/Controller/Account/CreatePost.php

    $this->_eventManager->dispatch(
        'customer_register_success',
        ['account_controller' => $this, 'customer' => $customer]
    );

Or either you can find the newly created customers by comparing the saved customer and previous customer data by observing customer_save_after_data_object event.

File: vendor\magento\module-customer\Model\ResourceModel\CustomerRepository.php

$this->eventManager->dispatch(
    'customer_save_after_data_object',
    [
        'customer_data_object' => $savedCustomer,
        'orig_customer_data_object' => $prevCustomerData,
        'delegate_data' => $delegatedNewOperation
            ? $delegatedNewOperation->getAdditionalData() : []
    ]
);