I have a bunch of Evods. They are great systems and a coil can last for many weeks with good care.
If I want to switch flavors in one, it gets a piping hot water bath. I unscrew it, remove the coil head and run everything in a measuring cup for a few minutes under scalding hot water. Then I let it sit for a few minutes. Rinse it again with cooler water. Shake out excess water, reassemble, fill and go. There's really no need to let it dry, but you can if you want.
If you don't let it dry, it will take a few power on draws to replace the water with your liquid. Just take it slow and you should be good.
After two or three tankfuls, it gets the same treatment but then it gets a dry burn. You can google "dry burn" and "Evod" and you'll see a bunch of videos on how-to.
I recommend that you go ahead and get a few more of those tanks, and a few boxes of replacement coil heads. On fixed voltage Ego systems, the stock 2.5 ohm coil heads are a little high, resistance-wise. The system really shines with coils rated at 1.8 to 2.2 ohms.
Congrats! You've got a great system.
