临渴穿井

lit. face thirst and dig a well (idiom); fig. not to make adequate provision / to act when it is too late

to face / to overlook / to arrive / to be (just) about to / just before

thirsty

to wear / to put on / to dress / to bore through / to pierce / to perforate / to penetrate / to pass through / to thread

a well / CL:口[kou3] / neat / orderly