When should I send a table-booking reminder on WhatsApp?

WhatsApp publishes no timing rule. A common pattern is one reminder the day before and one about 2 hours before. On the API, both usually need a utility template.

• Ask for the customer's OK to message them when they book. WhatsApp allows business messages only to people who gave their number and opted in.
• Free app: send the reminder by hand or from a saved quick reply.
• API: if the customer wrote to you in the last 24 hours you can send free-form text. Otherwise send an approved template.
• A plain reminder about the customer's own booking should count as utility. Add an offer and it becomes marketing (₹0.8631 in India against ₹0.115).
• Ask them to reply “Yes” or “Cancel”. A reply opens a new 24-hour window, so you can answer without a template.