This paper details exploratory research which treats architecting as a system. This human architecting system has a structure composed of decisions, interdependencies amongst decisions, decision making, decision makers and the decision-making environment. Agent-based modelling is used to model the architecting system, and simulation is used to visualise system behaviour over time. The goal is to map legitimate / optimal speed of architectural decision-making to an architecting system behaviour pattern. Knowing the appropriate behaviour pattern of early architecture evolution will provide a mechanism for fine-grained progress tracking of architectural design. Divergence from this behaviour pattern should provide early warning signs of an incomplete or overdone architecture.