As early as schematic design — ideally at SD. Pre-construction services produce: a detailed conceptual cost plan at the current design phase; a constructability review identifying design decisions that are expensive to build; value engineering options with specific dollar impacts; a long-lead material list for early ordering; and a preliminary production schedule. Changes made at the SD stage cost hours of design revision; the same changes at the CD stage cost days and permit re-submittal fees; after construction starts, they cost 10–50× more. The pre-construction services fee is modest relative to what they prevent.