Users and Roles Configuration: you will usually do this at the beginning, because it’s how you set up all persons that will be able to interact with your business processes.
Specific Domain Service Connectors (WorkItemHandlers in the class path): this could be done on demand, when you need a new system connector you will add it
A Business Process Model to run
A set of Forms for the Human Tasks (If you don’t provide this the application will generate dynamic forms for them): this needs to be done for each User Task that you include in your process. This is extremely important because it represent the screen that the end user will see to perform the task. The better the form the better the user can perform its job.