Validate dates on submission

I would like the ability to validate dates on issue submission, prior to getting to a workflow. for example, we have a date called Proposed Date that is entered by clients. For most issue types we use we have certain SLAs that would take 2-3 business days for an issue to be given an estimate and Commit Date. I would like to force a Proposed Date to be greater than or equal to today + 2 business days when an issue is submitted. This validation could also be dependent on Priority and Issue Type, so a Critical issue wouldn't have this limitation.

I would want the flexibility to use different validations based on the project, issue type, priority, and possibly other factors (haven't yet determined if any others would apply). Thanks.