Hi sochic ,
That's something unrelated to ATUM, but FYI, WooCommerce doesn't store a history, so you can't check your stock at some time in the past, sorry. You'd need complex calculations, including Orders served to get it. And you couldn't be sure of the results because the stock can be changed manually at any time.
You can use our ATUM Export Pro plugin to automatically export your stock all days into CSV files that you can check after, or the Action Logs plugin to store every product's stock movements. However, you'd only be able to access exports or stock changes since you installed and configured any (or) both plugins.