In a Salesforce CPQ Scoping Session, the first topic of discussion is typically Business Process Mapping.This involves understanding the current business processes and identifying areas where Salesforce CPQ can provide improvements. It's an essential step in the scoping process as it helps to define the project's scope and identify potential challenges earlyon. The other topics like Quote Document and e-signature, Order Management, and Products and Bundles are also important but they usually come after the business processes have been mapped and understood.

Reference

Get Started with Salesforce CPQ Unit | Salesforce Trailhead

CPQ Scoping Questionaire? : r/salesforce -Reddit

How To: Salesforce CPQ: Build a Bundle