Is there a minimum length of time that will be considered as sufficient regarding the "established relationship" between the core partners?

This PFA solicits proposals from applicants that have established researcher-community partnerships, defined as a research organization and a community organization with a previous or existing working relationship. They will serve as the core partnership of the award. In the application, the organizations representing the core partnership must describe their history of collaboration and demonstrate their ability and commitment to work together meaningfully. Providing information about the length of time the core partners have worked together may be one way of demonstrating their history of collaboration.