to do the action that you intend to do or need to do in order to achieve sth :
The rebels waited until nightfall before they made their move.
to do the action that you intend to do or need to do in order to achieve sth :
The rebels waited until nightfall before they made their move.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005