When Magik plays the top card of her deck, at what point is the next card in her deck turned faceup?

When playing the top card of her deck (which is the same process as playing a card from hand), Magik moves the card she is playing to the table in front of her during step 3 of the process outlined in the Initiating Abilities section of this rules reference. As soon as she does this, she turns the new top card of her deck faceup.