Best practice is to begin raised-floor installation at the center of the room, working outward. This minimizes alignment errors and ensures the tile grid is centered, which is critical for aisle containment and rack alignment.
Starting at the perimeter (A, B, D) causes cutting of tiles along both sides, misalignment with rack rows, and possible airflow inefficiencies. By starting at the center, tiles can be cut symmetrically around the edges, providing better aesthetics, balanced airflow, and structural stability.
Industry guidelines such as CISCA recommend this approach for raised floors in mission-critical spaces.