I meant what kind of growing medium. But I will assume Fox Farm Ocean Forest (as its damn common, and for good reason).
How often have you been watering with plain water? As in, how many times in the last week? I am sure you will be fine though. Don't stress it so much, and if it winds up tasting a lil funny (which I doubt) then you know better for next time.
Best way to tell if a plant is ready harvest is by its Trichromes (crystals). Grab a 30x microscope (they're really cheap) and check them out. If the majority are milky white then it is pretty close. Could even cut it down then if you want a more Sativa type high. Or, wait till about 20% or so have turned an amberish color for a more Indica "couch lock" type high.