QT tank

[Ctmadden]

All three of my fish recently got ich. I removed them from my tank and place them into a QT tank. Now, my QT is smaller than expected, do I can't leave my fish in there too long. It's only a 10g and I'm putting one fish at a time to reduce the possible amounts stress. I've had my potters angle in the QT for about 24 hours and the visible signs of the ich have diminished. I know that once ich Is your tank, it takes about 8 weeks to 'die off' but since my QT is small and the ich has fell when should I put the fish back in the tank?

Thanks