I think they open the nurses calendars 8 weeks at a time. So today you could only make an appointment for the next 8 weeks.
Your pre op nurse appointment is about 2-4 weeks before surgery (or at least mine was)… so they will probably be able to give it to you around 8-12 weeks before your op date??
Your post op appointments are usually made at your pre op appointments if the calendar is open by then if not they will phone you and organize it.
I don’t know if I’m making any sense but I hope this helps