Customizing Work flow approve trip (WS20000040)

When the trip expenses are submited, If the approver didn’t take any action(approve/reject) for 5 days (period of time can be changed for testing), Workflow notification should be issued to the next level approver. How and where the 5 day rule will be defined.

Is it possible to define 5 day rule as a parameter and create a tranaction so that business can change the number of days as company policy changes. If doable can you suggest the possible options?