Send expiration notifications XX days in advance (task)

I’d like to set up a task for sending an email notification 2 months in advance of an expiration date, however there is no option for this in the When-field.

I can always add another date field and make an equation for setting a reminder date, but I would rather have the ability to set;

When: [Date field] is [Exactly from current date] [XX] [Day/Weeks/Months/Years]