The period leading up to production/principal production where all elements necessary to proceed to production are finalised. At this stage a project will generally be fully financed and have most of the key elements in place, such as principal cast, director and cinematographer as well as a screenplay which is satisfactory to all the financiers.
The pre-production period would focus on locking in locations, cast members and crew, sourcing props, costumes & equipment, and creating a schedule for production and post-production.