Paint the exterior of the precast panels which is usually done in a rendered paint e.g. Wattyl Granolmpact or Taubman Armawall depending on the finish the client has selected. Texture rollers can do around windows and doors without cutting in before windows are installed. The concreters can pour the slab through trusses with boom pump and finish (Can complete roof first to weather proof house and line pump through panel openings).