Since you have a table for customers, a table for bookings, and a table for meetings, you could write a query to create a new data extension to use for a 'reminder' journey. I do something similar for reminding people 4 weeks, 2 weeks or 1 week away from an event.
I don't know your schema, but you can create something similar to the following: You'll basically need the email address and the meeting date (I'm not sure where you store this) in one data extension. Then you can run this every day to add people to the journey 2 days before the event.
SELECT EmailAddr, MeetingDate
WHERE [MeetingDate] >= DATEADD(DAY, 2, CAST(GETDATE() AS date))
AND [MeetingDate] < DATEADD(DAY, 3, CAST(GETDATE() AS date))