Buying from different pet stores is another factor to consider. Buying from different stores means you can't really pinpoint where the problem came from. Research store in your area, ask to see their waters salinity. Alot of stores, suppliers, wholesalers keep their salinity low cuz they believe it keeps the parasites from staying alive. In a way...they are keeping their fish in hypo-salinity then you have to take the fish home and acclimate for 3-4 hours and lets face it...we don't do that.
I wouldn't wait the 10 or so weeks reefpin. I would check all the pars and if they are all good...get a couple small fish that you want to keep and try them. I'm with globaldesigns...ich is always present in your tank. I have stated before in another related post that I have a Powder Blue Tang that gets ich all the time. In the beginning I would freak out and load up on the garlic or any other remedy I could think of but the ich came back. I gave up and just let him be...its been two years now and (not braggin or anything here) it is one of the nicest lookin PBs out there...and he still gets spots from time to time.
Sorry to sound winded reefpin...ich is a touchy subject...many reefers have different opinions on the subject. If it were me...I would be adding a couple small fish soon(tomorrow) to keep the cycle in check but check all the water pars first.