3.2. When Should You Create a BDD?
Often. You should create a BDD often.
That may seem like a glib answer, but it’s accurate. BDDs are not tied to any particular stage of the system life cycle or level of design. You and your team will create them (and refer to them) when you perform all the following systems engineering activities: stakeholder needs analysis, requirements definition, architectural design, performance analysis, test case development, and integration. And you often create a BDD in conjunction with other SysML diagrams to provide a complementary view of an aspect of your system of interest.
In short, you should—and will—create BDDs often.