At what phase should the charrette take place?

A charrette is a collaborative workshop that brings together various stakeholders and experts to address a particular design issue, such as sustainability, security, or accessibility. A charrette should take place at the beginning of the project, when the project goals, scope, and budget are being defined, and when the most impact can be made with the least cost. A charrette can help establish a shared vision, identify potential challenges and opportunities, and generate innovative and integrated solutions.

 A Handbook for Planning and Conducting Charrettes for High-Performance Projects, page 1-2; LEED v4 Green Associate Candidate Handbook, page 12.