I broke up the sql and got the following results. So the least date for today would be '13-NOV-02' which is tomorrow. When you run it on Friday it will be '18-NOV-02'

SQL> SELECT NEXT_DAY(SYSDATE, 'WEDNESDAY') FROM DUAL;
13-NOV-02
SQL> SELECT NEXT_DAY(SYSDATE, 'THURSDAY') FROM DUAL;
14-NOV-02
SQL> SELECT NEXT_DAY(SYSDATE, 'FRIDAY') FROM DUAL;
15-NOV-02
SQL> SELECT NEXT_DAY(SYSDATE, 'MONDAY') FROM DUAL;
18-NOV-02
SQL> SELECT NEXT_DAY(SYSDATE, 'TUESDAY') FROM DUAL;
19-NOV-02