How far in advance should I start the process before I want to move someone in?

As a general planning guide, budget six to twelve months from your first feasibility check to a finished, occupancy-ready unit for a detached ADU, and three to six months for a basement apartment conversion – though a project needing a Committee of Adjustment variance can add two to four months on top of either. These are general ranges, not a schedule for your specific project; your written quote will include a project-specific timeline.