Start doing WCs and running carbon. It is not necessary to completely remove all of the copper after the 30 day treatment period. You just want to get most of it out. During the fallow period, continue to observe your fish in QT for symptoms of ich just in case. Even behavioral symptoms such as heavy breathing, head twitching, rubbing, flashing should raise a red flag. Also be on the lookout for bacterial infections, as copper probably compromises a fish's immune system somewhat. You also might want to deworm them using Prazipro, if you haven't done so already.