Section 3--109. Definite Time

(1)  An instrument is payable at a definite time if by its terms it is
  payable
         (a) on or before a stated date or  at  a  fixed  period  after  a
             stated date; or
         (b) at a fixed period after sight; or
         (c) at a definite time subject to any acceleration; or
         (d) at  a definite time subject to extension at the option of the
             holder, or to extension to a further  definite  time  at  the
             option  of  the  maker  or  acceptor or automatically upon or
             after a specified act or event.
    (2) An instrument which by its terms is otherwise payable only upon an
  act or event uncertain as to time of occurrence  is  not  payable  at  a
  definite time even though the act or event has occurred.