@Yuggyuy
Running the ./cvsecurity.py enable_protection -i InstanceID
script should only take a few minutes. Time taken to reboot is a little harder to estimate. It will run the script, stop the cluster and unmount it and all the disks, then start the cluster and remount everything.
It would be best to run the script 1 node at a time, if it completes without errors move to the next and run it. Once it is ran on all 6 nodes, then you can reboot all at the same time. That way it will minimize downtime, instead of doing 1 at time. But up to customer, I know some people like to be on the cautious side.