at the first sign

:  preceding all others in time, order, or importance: such as

:  earliest

:  being the lowest forward gear or speed of a motor vehicle

:  before another in time, space, or importance

:  for the first time

:  in preference to something else :  sooner

:  something that is first: such as

:  the first occurrence or item of a kind

:  the first forward gear or speed of a motor vehicle

:  a motion or gesture by which a thought is expressed or a command or wish made known

:  signal

:  a fundamental linguistic unit that designates an object or relation or has a purely syntactic function

:  cross

:  to place a sign on or mark by signs

:  to represent or indicate by a sign