[Logician]

Getting a lot of notifications happens if you applied STEP2 wrongly and entered a wrong date or in a wrong format. So the hack wouldn't know your real installation date and in the first run will greet birthdays starting from your wrongly entered date until today (thus will produce a lot of greetings.)

It will stop "today"'s date is reached so it is safe to assume that the date in the database is correct now. Thus you shouldn't have any problems from now on. It will go on greeting normally from now on as date is now ok. But if you want to make sure, run this query and confirm date is today or yesterday:
[sql]
SELECT leftdate from timetick where action='birthday';
[/sql]

If you want to remove the hack, you can simply delete the hack code you inserted in index.php. This will uninstall (and stop) the hack.