n8n Google Sheets Workflow: Post-Visit Reviews & Rebooking

Turn completed visits into timely WhatsApp follow-ups—without duplicates

This n8n workflow automatically checks completed visits every 12 hours, validates the data, then sends either a WhatsApp review request for first-time customers or a rebooking nudge for returning customers—while skipping invalid, out-of-window, or already-messaged appointments.

What this workflow does

• Runs on a schedule: uses a schedule trigger to process visits every 12 hours.
• Loads and validates visit rows: confirms each record includes appointment ID, customer name, phone number, and a parseable visit time.
• Handles invalid data safely: routes invalid rows to an error log and continues processing valid records.
• Applies a post-visit timing window: filters eligible visits to a 20–34 hour window after the visit time, skipping visits that are not yet due or already outside the range.
• Prevents duplicate messages: tracks which appointment IDs have already received a follow-up, so customers aren’t contacted multiple times.
• Creates the outbound message: builds a WhatsApp message that asks first-time customers for a review and nudges returning customers to rebook based on treatment type.
• Sends and logs: uses a placeholder send step (to replace with your messaging provider) and logs whether a review ask or rebooking nudge was sent.

Use cases

• Day-to-day SaaS or service operations that want consistent post-visit communication.
• Rebooking funnels for clinics/salons/spa teams using appointment-based follow-ups tied to treatment type.
• Automation engineers who need a reliable pattern for validation, time-window filtering, and deduplication in n8n.

Technical details

• Tech stack / nodes used: schedule trigger, if, code, sticky note.
• Input setup: replace the demo visit source with your production data source (e.g., a Google Sheets spreadsheet) with fields like appointment_id, customer_name, phone, visited_at, treatment, and first_visit.
• Messaging: replace the placeholder send step with your chosen integration (e.g., WhatsApp Business Cloud, SMS, or email).