Shism is right, don't take a victory lap yet. If you haven't seen signs pop up in 4-6 weeks, only then can you be fairly sure you've beaten it. Be prepared for another wave - hope for the best but plan for the worst. Also, as the ich cysts may have just dropped off the tang & hatched, keep an eye on all your fish over the next month or so.
Patience, monitoring and understanding is the only reason I am confident that my Proto Marin treatment worked in my tank. Keeping in mind that a fish can't just beat ich, they only tolerate the wave, I'm going on what would be my third cycle without any sign. If it was still there, or treatment only partially effective, I would expect to see some by now.
Also, the ONLY reason I didn't quarantine this fish at purchase was that I had just completed a tank move and accidentally cracked the drilled overflow on my QT. Had I quarantined, I could have safely treated this fish on its own without risk to the rest of the tank.