If you look at a booster pack that is being drafted during the current draft round, you may do so after a player has drafted a card from that booster pack and before the next player has been passed the cards. As a courtesy, you may inform the player currently looking at the booster pack that you'll be looking at it next, before it's passed to the next player.

If you use Whispergear Sneak during the first draft round to look at an unopened booster pack, the owner of that booster pack doesn't have to "open" that booster pack for the next draft round, although they may do so.

If you look at a booster pack not being drafted during the current draft round, open that booster pack, look at the cards, and return them in a face-down pile.