This is the 4114th most frequent Korean word.
전날까지
"Until the day before."
The word '전날까지' here indicates the time frame up to the day before the mentioned event, setting a context of past completion.
전날까지 준비를 마쳤어요.
I had finished the preparations by the previous day.
In this sentence, '전날까지' is used to specify a period that lasted up to the previous day which affected the situation described.
전날까지는 비가 와서 면회가 취소되었습니다.
It rained until the day before, so the visitation was canceled.
Here, '전날까지' shows the limit of time (up to the day before) during which a condition continued that led to a decision.