Hi Jeff,
Thanks for your feedback.
To answer your questions, at the moment I try to make it a batch campaign which runs daily at 9 AM in the morning. Reason being that I don't really see how to use a trigger in this case, as I want to use a date field (lead.bePART Sales Certificate Acquired_) which contains the exact date when a person passed the exam. Also, I am using data going back to 2011, when were not yet using Marketo + each value is different (people did not pass the exam on the same date).
Concerning your suggestion, what would be the best way to go at it, as it would mean creating another field in the database just for this purpose?
Also it seems that you can only add a value in number of days, see below: