You can create an automated response (selecting the event when ODS has completed) and you will receive an Email when it is done
You can do a querie based to the Event ID :
1202: On-demand scan started (Info)
1203: On Demand scan complete (Info)
Be carefull that you have enabled this event onto the Server Settings > Event Filtering.
This Events are disabled by default.
I'm trying to figure out how to do a similar thing to you. From what I've gathered so far, you can get a simple status on whether the scan has been completed or not using the Event IDs and methods mentioned above in this thread by Folcan and llamamecomoquieras.
I'm trying to get a more complete report gathered and have started a thread here, if you'd like to follow that & contribute any ideas you may have.