The project: a 2-story, 18,000 sq ft mixed-use retail/office building, modeled across architectural, structural, mechanical, electrical, and plumbing disciplines as linked Revit files, federated for coordination. Every later step in this series depends on this setup being right.
A multi-discipline BIM project doesn't start with one model — it starts with a linked-model structure: each discipline (architectural, structural, mechanical, electrical, plumbing) builds and owns its own Revit file, and every other discipline links that file in as a read-only reference for coordination. For this 18,000 sq ft building, that means 5 separate discipline models, each linked into the others, all sharing one common coordinate system and set of levels/grids established at project setup — get the shared coordinates wrong at this stage and every discipline's model will be misaligned relative to the others for the rest of the project.
Project setup also establishes the framework everything downstream depends on: levels (matching this building's 2 stories plus roof), grids (the structural column grid every discipline references for coordination), worksets (dividing each discipline's own model into manageable, separately-loadable pieces for team collaboration), and shared parameters (custom data fields — like a room's occupancy type or a duct's insulation spec — that need to be defined identically across every discipline's model so schedules and coordination checks in later steps actually work).
File naming and organization conventions get locked in here too — a consistent naming scheme (project number, discipline code, model type) isn't administrative overhead, it's what makes Step 3's clash coordination and Step 5's sheet production actually navigable once the project has 5 linked models and dozens of views and sheets. Getting this foundation right is genuinely the difference between a coordination process that works smoothly in Step 3 and one that spends half its meeting time just figuring out which model a given clash belongs to.