Best practices for my customer who is now using an external master enrollment DB

Granted, they were experimenting with the system.  When I synced up the external DB to my moodle site this week, I noticed a *few issues with the now *master enrollment table.

1 - there is no constraint prohibiting the entry of duplicate enrollment records.
2 - my customer created a lot of duplicate records in the table.
3 - I need to provide some clarification for *best practices pertaining to entering enrollment records.

Directions for my customer pertaining to creating/entering records in the enrollment table

1 - When you enter a record in the master enrollment table.  Wait approx. 15 minutes before checking to see if its made its way into the appropriate moodle course.  There is a 15 minute interval for the cron script to run.  The cron script is what says to moodle "go check the master enrollment table for any new enrollments and if you find any usernames not in a course with an external database enrollment type, then put it there.".

2 - If you enter a record and does see it in the moodle course.  Do NOT enter another record and check again.  If you can't wait, then you can browse the cron script and make it run.  This will force the sync of moodle and the external DB. 

3 - If you are certain the sync has occurred and you STILL don't see the enrollment in the appropriate course, then check, very carefully, the short name in the course.  That is the field that links the master external DB to moodle.

4 - Browse the cron script by entering in your browser siteURl/admin/cron.php.

5 - If you added a new enrollment for an account, you can also LOG into moodle using that account.  Logging into moodle also caused moodle to say "let me get a fresh set of enrollment data".

6 - The duplicate records in the enrollment table are not really that problematic, they simply get ignored the 2nd , 3rd etc time the same record is encountered by moodle.  In other works.  If there is already an enrollment in a course matching the username and enrollment type (external database), then the subsequent ones are ignored or not inserted again.  No harm no foul, except its just stupid to add the duplicates.