This was my basic approach:
1) Spend the first 6 months really tackling your basic ophtho competencies. If there's time on top of this, try and interact a bit with the OCP faculty to make sure that you really want to commit. Unfortunately, at most places you'll have to decide before having extensive experience as an intraocular surgeon.
2) Prioritize the first year OKAPs and start studying a few months in (after this you'll have two rounds that don't count for anything). Now with the SF Match, all programs will see your scores whether they specifically ask for them or not. While this seems like a stupid thing to focus on, preceptors will definitely notice your scores if they're particularly good or bad. I'd suggest OphthoQuestions (USMLE world -type question bank) and a review like Chern or Friedman. Read the BCSC books that interest you, but this is not an efficient means of preparation.
3) After 6 months to a year, start working on some research with a faculty mentor. Try and do a few case reports here and there if the opportunities arise. Try and submit something to the ASOPRS fall meeting (deadline end of May of your first year).