Korean phrase
~ 몇 일 전에 알려야 하나요? ~ myeot il cheo ne al lyeo ya ha na yo
Meaning
Regarding ___, how many days in advance should I let you know?
When to use it
It asks how much advance notice is needed. It is a polite but fairly casual way to check when notice should be given, including for attendance.
Example dialogue
참석 여부는 몇 일 전에 알려야 하나요? cham seok yeo bu neun myeot il cheo ne al lyeo ya ha na yo
How many days in advance should I let you know whether I will attend?
보통 이틀 전까지 알려주시면 준비하기 충분해요. po tong i teul cheon kka ji al lyeo ju si myeon chun bi ha gi chung bun hae yo
Usually, if you let me know two or more days in advance, that's enough time to prepare.