If it's only been a day or 2 since it started I would honestly say no tasting wouldn't really tell you anything, and oxidation is the results of oxygen in the final stages, as it is fermenting the gasses prevent/ force any oxygen out...now natural fermentation isn't always bad especially if it's slow and just started... by clearing/sterilizing it with campden tablets means its more clean and controlled with the type of yeast used flavor, potential alc, and so on, (a little out side yeast will probably die frome the amount of alc if its just starting or won't be enough to make a difference)and gives you more time to work, if it has just started and you have not added anything else you can re sterilize all equipment and add some more to the must and stirr few times...or you can just go ahead and start your full prosses add your air lock and let it go