What happens when your opponent's deck has more than 3 candles in it?
The Candles shuffled into your opponents deck are not tied to a specific The Darkness minion. In other words, if you shuffle more than 3 Candle cards into your opponent's deck, then all of your Darkness minions will "wake up" sooner.
This is can be shown simply enough in a single-player practice match with the Innkeeper, but it can also be shown as the strategy of shuffling multiple Candles was the main point of a deck suggested by Mike Donais, a senior game designer of Hearthstone.
So your deck has great potential!