Raise your tank temp to 78 or so. Speeds life cycle of ich. Or so I have heard.
76 days is the recommended fallow period, as one study showed ich surviving that long, however there is some debate to that as it was done in quite cold water.
Absolute minimum time is 45 days and that will rid you of most ich strains. Note, most strains, not all.
Once your chosen fallow time is over, I would personally recommend acclimating a couple black mollies to saltwater and put them in for a couple weeks to confirm your fallow was successful. If they do get infected, treat them how you would a proper marine fish with ich, and begin fallow anew. They make awesome algae eaters, so might as well keep them around.