Remember that H2S is a very potent compound. As little as 3 parts per million can knock you over. Consider just how little H2S is in your wine..
With copper sulfate, please remember that this is a poison. You do not need a whole lot. A little goes a long way.
before using your copper sulfate, you should first try a splash racking. You may find that simple aeration is enough to vastly improve your wine.
If aeration did not do the trick, then I would set up a bench trial to determine exactly how much copper sulfate to add. Set up 5 or so glasses each having a metered amount of wine (500ml). Leave the first one alone as a control and add a single drop to the second, two drops into the third, and so forth. Then check to see at what point the smell is gone. This should give you an idea on how much to add.
BTW, Redueless is a much more effective and safe method of introducing copper into your wine.