Official comment
One of our developers recently threw together some code to make this happen - setting a countdown timer based on the value of a contact's Date Field
If you set up a rule to set a custom date field to today's date, you can have our countdown timer pull from that contact's set date field via a merge field and PURL, and offset that by however many days you like.
Here's the page with the custom code to add to the landing page:
The JavaScript posted is looking for dates formatted in the US method of MM/DD/YYYY, where MM = Month (01 - 12), DD= Day (01 - 31) and YYYY = Year (2017, 2018, etc.)
When you create the merge field the date field formatter pops up a box to format the date. Use the "Standard Slash" format. The Merge Field will have "ss+0" at the end of it, standing for "standard slash plus 0 days", similar to this:
[My Custom Date Field ss+0]
To offset the date, change the 0 to however many days you like!
