on/at first acquaintance

:  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

:  the state of being acquainted

:  personal knowledge :  familiarity

:  the persons with whom one is acquainted