My advice is this:
Go to you LFS, ask them what their salinity is in their tanks. If they say 1.018-1.021, find. Set your QT up at that salinity. Once you introduce fish into the QT tank, begin to lower it SLOWLY. 1.014 is where the bacteria begin to stop working. You can go down safely to 1.009. I've done it. You just need to keep a bottle of amquel on hand and test parameters twice a day. After four weeks, raise the salinity slowly. Once you have the salinity at the range you need, monitor the fish for another 4 weeks. CLOSELY. Any white and its back to the 1.009. Keep in mind, that Ich has stages and catching it at the right stage, it can be cured within 4 weeks. But your conservative estimate is 8-10 weeks. If you have this time, do it. I usually do two weeks at .009, then 2 at .014, 2 at 1.018 etc. That seems to work best for me.
Number 1 rule of WC and CB fish: QT them like theirs no tomorrow