If you have a motivated instructor who will put a challenging and fun program together for you, you might as well take the course asap. Its a great opportunity to do 5 directed dives with an instructor as a fellow diver, vs being a new student.
You should read the entire Adventures in Diving book and do all of the knowledge reviews.
When I teach the class, we highlight specialties that you may be interested in and use additional videos and material to delve further into each of those interesting specialties.
We also have a review/refresher in the pool along with a buoyancy/trim/finning technique workshop. Then its off to do the dives. You will be required to do a deep dive and and underwater navigation dive. You and your instructor can choose three additional dives.
You should emerge from the class as an enlightened diver, not necessarily "advanced." but probably more directed, disciplined and motivated!
Have fun and good luck! you will really enjoy your rescue class too.