Invertebrates are not susceptible to ick, so there's no need to do that. You can get your RBTA and put it in your tank at any time. If your clowns we're expose to the ick outbreak i would treat them with cupramine for 14 days and after treatment is done observe for another 30 days to make sure they are healthy, the same will apply for any other fish that survived the outbreak. One more thing, don't be bumb out if your clowns don't host your anemones, it's a toss up when it comes to that, some do and some don't, mine don't care about my RBTA they prefer to swim around, I guess is a case by case basis, lots of articles about the behavior but no one seems to figure out why some do and some don't, so get you RBTA, get your clowns healthy and have fun with it!