Final answer:
The configuration of a user view for a case life cycle step in App Studio is done at the earliest during the design time phase, which precedes run time, implementation, or deployment.
Step-by-step explanation:
The earliest opportunity to configure a user view for a step in a case life cycle in App Studio is a) At Design Time. During the design phase of the case life cycle, developers can configure the user interface by specifying fields, controls, and other elements that will be presented to the user when they perform a step in a case. In Pega's App Studio, the design time is when the case types, views, and processes are defined and before the application moves into run time, implementation, or deployment phases.