In fact.
Long before they began their cross-universal journey, Jiang Hui had already sensed their approach.
However, it wasn't because he had issued the order in advance that the two were allowed to enter the Immortal Domain.
Maintaining a certain level of mystique is the first and foremost principle that the Sacrificial Spirit must follow.
Even those lower-level Sacrificial Spirits from the outer realms wouldn't just appear without reason; most of the time, they pass their time in silence, only showing themselves if their followers face a great disaster or summon them with grand and solemn rituals.
Though he was not truly a Sacrificial Spirit, he walked the path of gaining followers through faith and should do the same.
Therefore, under normal circumstances, Jiang Hui would not easily show himself or issue his orders arbitrarily.