N8N WhatsApp Auto-Send Workflow

I need an end-to-end n8n workflow that can schedule and send WhatsApp messages without relying on any paid SaaS such as WATI. Here is exactly what the flow must do:

• Input: I enter (or import) phone number, send-on date & time, and fully custom content for each recipient—plain text plus, when needed, a single image.
• Scheduling: n8n queues each item and triggers at the specified moment, respecting my local timezone.
• Delivery: the message is dispatched through a zero-monthly-fee solution—WhatsApp Cloud API, self-hosted gateway, or another cost-free alternative you recommend—and the run result is logged back to n8n for auditing.
• Confirmation: success or error returned so I can see what happened.

I’m new to n8n, so please include clear, reproducible setup instructions and a quick call or video walkthrough once the flow is ready. The final hand-over will be:

1. Exported n8n workflow (.json) with any custom credentials placeholders.
2. Written guide covering environment variables, WhatsApp API/app registration, and how to add more messages later.
3. Short live session (recordable) to confirm it works on my server.

If you have prior examples of WhatsApp integrations in n8n, let me know—seeing them helps me decide quickly.
template :
https://docs.google.com/spreadsheets/d/1C8aAYyFyzHNHOBmww2ob2qS1pbwA8DNX24C8zLmX7pE/edit?usp=sharing