Austin's primary focus is on courses and finishing 36 Faces, so he not booking readings very often at this time. When he does take appointments, it tends be a limited number of slots for the coming quarter that fill up on a first-come, first-served basis, typically within minutes.
If you would like the opportunity for a consultation, the best way is to join his Patreon, which is functionally free at this time since writing for The Online Almanac project is on hiatus. Patrons are still the first people who get invitations to book, and receive priority. The Mailing List comes second.