Since you didn’t quarantine any fish of your current fish you have a few things to think about. Your current livestock could possibly have some sort of disease without showing outward symptoms. Maybe maybe not. Would they infect the newcomers possibly? If you can guarantee that your current fish are disease free, definitely quarantine. It’s kind of like rolling the dice. Some people never quarantine, and never have issues. Some people risk it and have velvet wipe out a whole display over night. Lesson learned the hard way. Some would rather practice ich management than eradication. Some individuals like PaulB thinks quarantine tanks are silly!!! I completely respect his opinion and knowledge on the matter.
There is nothing special about divers den quarantine practices. Lol! I wouldn't even call it quarantining. More of conditioning and observation period like
@ca1ore said. I wouldn't trust any source myself. When it comes to quarantining, I’m more a treat prophylactically person than sit back and observe. But, if you start down the road of treating everything, it doesn’t stop with fish. It goes for everything wet. Corals, snails, anemones, etc.... I have been using hotrocks method for the last several batches of fish with great success.
I found using two Quarantine tanks identical to each other makes life much easier. Having a second sterile and cycled quarantine to transfer fish to after two weeks in copper at therapeutic levels minimizes unecessary prolonged exposer.
If you decide to go the treatment route, I would entertain this method. If you’d like to read a bit more about this quarantine method it can found here.
https://www.reef2reef.com/threads/my-current-qt-process.483371/
Also here’s a good write up on how to quarantine.
Lots of good info here.
https://www.reef2reef.com/threads/how-to-quarantine.189815/
Here’s a useful chart/guideline for treating fish with copper and Chloriquine.
https://www.reef2reef.com/threads/fish-and-treatment-guidelines-with-chart.283450/
Here’s another guide for coral and invert timeframes.
https://www.reef2reef.com/threads/coral-invert-quarantine-time-frames.334584/