1. Create a rule referencing the Export - Created Date:

2. Select 'Between' and then enter the below functions:


Change the numbers within the brackets to set the Proximity to the created date e.g. -14 & 0 will show any products created within the last 14 days

3. Then define the action:

Note: if you want to convert a custom date you can use this formula:
{@@=System.DateTime.ParseExact("13/05/2014", "dd/MM/yyyy", "")}

dd = day
MM = month
yyyy = year