Upgrade kong gateway (DBLess) 2.0 to 2.8

Currently, I am running on DBLess Kong 2.0 and I would like to upgrade the kong to 2.8. Could you please guild me how can I do the upgrade with the minimal downtime?

In our environment, we changed port of the old Helm release and then deployed another Helm release to replace the old one.
If everything is fine delete the old, if not switch back.