This is the 6562nd most frequent Korean word.
오전부터
"From the morning."
The word "오전부터" indicates the starting point in time (from the morning) for the activity (studying) in the sentence.
나는 오전부터 공부를 시작했어요.
I started studying from the morning.
Here, "오전부터" specifies the time (from the morning) when the meeting started.
그들은 오전부터 회의를 했습니다.
They had a meeting from the morning.
In this sentence, "오전부터" highlights the onset time (from the morning) of the rain, which aligns with the predictive context of the sentence.