Joshua 2:21

‘ And she said, “Let it be as you have said.” And she sent them away, and they departed, and she bound the scarlet line in the window.'

She sent the spies away to safety and ensured her own safety by fastening the scarlet cord in the window. Not necessarily immediately, but in good time for it to do its work. (It does not say when she did it. It is we, not they, who are slaves to chronology).