What Marks the Beginning of a Player’s Turn (Article ID 153)

Abstract:  One might think that a player’s turn begins when the previous player discards a tile but that is not the case. The reason for this is that turns can be interrupted when another player claims the discard to make an exposure. Therefore, a player’s turn officially begins when they either pick a tile from the wall or call a discard.

Source: Back of the NMJL card, panel 1, “A player’s turn begins when they either pick or claim a tile.”