Longops is a great way to monitor things that take some time to do work. There's an easy example of using longops on oracle-base here. I borrowed the script from there and put it into a file named my_slow_thing.sql. Now here's a nice example of what's possible with sqlcl.
The easy way to using this is add it to your login.sql which is what I did. Of course the script could run at anytime instead of in the login.sql