Nintex Forms, SharePoint 2013, Date Field - Validate that Date Chosen is not Today

Hello Community, I am working with Nintex Forms in SharePoint 2013, and I want to create a validation check for a Date field. I need the field to throw a validation error if the user enters a date that is less than or equal to today, so the pseudo logic would look like this: If Date <= Today Then Invalid These are the types of validation codes I've used (but so far nothing has worked): {Self}<=TODAY DateField<=TODAY Has anyone else solved this kind of issue before? If so please provide guidance and code examples. Thanks! Tom