Starting your 14g with live rock is basically a kind of quarantine anyway, observational at the very least. If you start it with the live rock, it will be a few weeks anyway for it to get established. You will be well entertained with the goodies that came with it. In fact you may have to feed your new tank with phyto etc. even before you put one fish in. You can take a page out of
@Paul B 's book and view that a healthy fish that is nutritionally happy will be able to fight off stress related diseases. Clownfish I feel are pretty hardy creatures in the first place. I think you are thinking too much about it. Just enjoy the experience, and learn by observation.