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

: in the first place

: for the first time

: one that is number one in a series — see Table of Numbers

: something that is first: such as

: the first occurrence or item of a kind

: 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