Historical Rules · 5 October 2018
Rule 718.4
Official source text from the 5 October 2018 Rules release
The effect that restarts the game finishes resolving just before the first turn’s untap step. If the spell or ability that generated that effect has additional instructions, those instructions are followed at this time. No player has priority, and any triggered abilities that trigger as a result will go on the stack the next time a player receives priority, usually during the first turn’s upkeep step.