How can I have a TimeStamp addition for a module

Hi All,
I am a new member to the community and SuiteCRM.
I would like to know the process to set a workflow for the following condition:
“A case has been created and I would like an email for the condition if the case has not been modified/replied since the last 4 days”
I can setup the basic workflow but I am confused in setting an additional time stamp for an action in the workflow.
Kindly guide with the condition,etc to set up the workflow.

THanks All

Create a condition:

Date Modified
Less Than or Equal To
Now - X Days

Will need to set a Flag on this or an email will keep sending out as the condition will always be met.

Thanks for the reply. How do I setup the Flag for a particular condition. Is it somethings that is needed to be done via code or can it be done via admin section itself.