Download WooCommerce SKU Image Uploader, It is a WordPress Plugins on CodeCanyon.
Make bulk operation with images uploading to WooCommerce products easier with Woocommerce Images import by SKU plugin by WEB Devise Co.
All you need to make the process of product image import simple is to create the folder in wp-content and upload to the server images with SKU numbers in the images files names. All other work with import could be done by the plugin.
WooCommerce Images import by SKU plugin could work with Simple and Variable products.
In SKU you could use both figures and letters. But as a recommendation for your e-commerce business, please try to make unique your SKU for products as much as possible to make easier manipulation with products by SKU with this plugin and all other of our products. For this purpose, you could use prefixes for a group of products, for instance.
The plugin includes logging for operations to show you the processing.
For all process operations and how to use plugins please check the documentation (archive with plugin include it).