User Creation Date
To check the creation date for a specific user, we can query ALL_USERS.
First of all, we format the date time of current session.
SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
Session altered.
SQL> select created from all_users where username = 'HR';
CREATED
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2020-07-20 23:33:02
As you can see, the user is created as shown.