How to find out the how long product import takes?

I am using Woocommerce’s built in product import page.

I need to know how long it takes to import 1,000 products so I can estimate the time to load an arbitrary number of products (say 2,000 3,000 and so on).

This is so I can size the import to be as efficient as possible (2,000 product imports might take faster than 2 chunks of 1,000 product imports).