Which documents should I have ready when the auditor arrives?

At a minimum: the food safety plan with its hazard analysis, the procedures (SOPs), monitoring records (temperatures, cleaning and sanitation), corrective actions, verification (calibration and records review), allergen control, traceability and your latest mock recall, environmental monitoring, supplier approval, staff training, pest control, internal audits, management review, food fraud and food defense plans, and previous audit reports with their close-out. What shows the most is being able to find any record in minutes, not hours.