Multi-agent systems are most often designed for a purpose, to perform one or more tasks, to achieve one or more goals for human users. Current research on multi-agent system design focuses primarily on MAS functionality, structure and (emergent) behaviour. Very little research focuses on interaction between human users and multi-agent systems. Trust in multi-agent systems, however, mandates consideration of their interaction. Recent research on the design of trust (YUPTA) in human (online) collaboration emphasizes the importance of time in interaction: synchronization, rhythm and duration are elements that determine whether trust emerges and is maintained. This paper argues that similarly temporal engagement between human beings and multi-agent systems must be explicitly designed and implemented for trust in MAS to be acquired.