The book page shows a default catalog, and catalogs allow sorting of the services
There are two options, nearest availability first and custom/manual sorting. "Nearest availability first" is most relevant when workshops or courses are sold. For appointment-based services where the same staff delivers the service, most services will show the same earliest availability, making this sorting obsolete (and random).
For Custom sorting, you can drag the services to sort.
Here is a video to show it live: