Automatic Transmission

MY 2003 TOYOTA SURF( A.T. A34f) NEEDS 5 MINUTES TO SHIFT INTO REVERSE WHEN THE ENGINE IS OFF FOR MORE THAN 45 MINUTES. THE FIRST GEAR DOES NOT ENGAGE AT TRAFIC LIGHT BEFORE A KM. I HAD THE VAIVE BODY CHECKED TWICE AND REVERSE DISCS CHANGED. WHEN THE ENGINE IS WARM EVERYTHING IS PERFECT. ANYBODY CAN HELP PLEASE ???