• Remove all furniture (if possible),
• Cover floors with painters drop cloths and furniture with plastic,
• Remove damaged  drywall, plaster,
• Support  the rest of drywall or plaster with board adhesive, screws, studs,
• Seal damaged areas with oil-based primer,
• Install insulation (if required),
• Install drywall support: for small damages – stiff mesh, for bigger damages – wooden studs.
• Install drywall,
• In some cases we install metal mesh and apply plaster compound,
• Tape, patch, sand and prime with PVA primer,
• Paint the ceiling with flat or semi-gloss  (Bathroom) paint.
• Clean the job site.
• Get paid

Usually the whole process takes one day.