Adding time to an event that runs on a weekly basis
There are three things you should do with this


Change DROP DATABASE to DROP DATABASE IF EXISTS
Add INTERVAL 11 HOUR to the START (as mentioned by @ypercube)
Add ON COMPLETION PRESERVE to make it a repeatable event so you don't have to create it again.


Here are the changes

DELIMITER $$    
CREATE EVENT le_drop_database
ON SCHEDULE
  EVERY 1 WEEK
STARTS CURRENT_DATE + INTERVAL 3 - WEEKDAY(CURRENT_DATE) DAY + INTERVAL 11 HOUR DO
ON COMPLETION PRESERVE
BEGIN
  DROP DATABASE IF EXISTS carbon;
END $$
DELIMITER ;


I hope this event is not in the carbon database

If you ever need to disable the event, just run

ALTER EVENT le_drop_database DISABLE;


to reenable

ALTER EVENT le_drop_database ENABLE;


CAVEAT

Please make sure you have this in my.cnf

[mysqld]
event_scheduler=1


You can enable this without restarting mysql by running

mysql&gt; SET GLOBAL event_scheduler = 1;


Give it a Try !!!