Separate a request from a confirmed booking
A customer asking for Tuesday afternoon is different from an appointment being accepted. The workflow should make that distinction visible to the customer and your staff.
We agree on who can confirm a booking, which calendar is authoritative, and what happens when a requested time is unavailable. A request can stay with staff when the decision needs their judgment.
Keep follow-up tied to what actually happened
Reminders should use the current appointment details. Changes, cancellations, and replies need to affect later messages so the customer does not receive outdated instructions.
An illustrative flow could collect intake details, record an accepted appointment, and prepare the next staff task. The exact messages, channels, and supported connections are defined for your business before launch.