Wait as long as possible before activating this card since extra monsters added to your graveyard after activating this card are not counted towards the total.
A good trick would be to use "Fiend Comedian" to send weak monsters from your deck to the graveyard and enhance the effect of this card. If you guess wrong (or right depending on how you look at the situation), you can always use "Second Coin Toss" to get a better outcome.
Keep in mind that "Fiend Comedian" sends cards from the top of the Deck to the Graveyard, you don't get to choose which cards to send (as the above tip would suggest). Regardless of that fact, it still makes this card more effective.