If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash. (You may cast them any time you could cast an instant.)
6/8/2016 A player’s “opening hand” is the hand of cards the player has after all players have taken mulligans and “scryed” if applicable. If players have any cards in hand that allow actions to be taken with them from a player’s opening hand, the starting player takes all such actions first in any order, followed by each other player in turn order. Then the first turn begins.