HPLIP Catch-22: Need IP to install printer / need to install to get IP
Solution 1:
Print a configuration page by pressing the Wireless button and the Information button on your printer at the same time. It will, among many other items, list its current IP address.
Solution 2:
If using a router, log in to the router admin page (usually found from entering the address 192.168.1.1 on a browser page) where you will be able to see the IPs of all connected devices after selecting the appropriate page.