ORA-01722: The specified number was invalid when truncating timestamp
The FIRST_LOAD_TIME column is actually a VARCHAR2 (which is a bit strange to me) so;

select to_date(first_load_time,'YYYY-MM-DD/HH24:MI:SS') from v$sql


Will show it as a date by applying the function TO_DATE.
Simply add a TRUNC to the beginning to get the value you want;

select TRUNC(to_date(first_load_time,'YYYY-MM-DD/HH24:MI:SS')) from v$sql