Section 763. Notice of motion

Notice of motion under sections seven hundred
  sixty-one  or seven hundred sixty-two, including the court's own motion,
  shall be served upon  parties  and  any  agency  or  institution  having
  custody  of  the child not less than seven days prior to the return date
  of the motion. The persons on whom the notice of motion is served  shall
  answer  the  motion  not  less  than two days before the return date. On
  examining the motion and answer and, in its  discretion,  after  hearing
  argument,  the  court  shall  enter  an  order,  granting or denying the
  motion.