I don't recommend going to the exam and choosing it there; you wouldn't have the detailed knowledge that the lit exam demands. Plus, you would waste time reading several sets of three passages with the additional burden of CHOOSING which one to do (very stressful!)...
You would hear people telling you to study a back-up text (i.e. 3 texts) just in case there are bad passages on the exam- but a realllly good teacher once told me if you know your text well enough there shouldn't be hard passages for you (you should be prepared for any passages they throw at you)! Also, consider your other subjects; now that there are no mid-years, you would be studying 5 subjects or so quite intensively towards end of the year so I don't think you would be able to study 3 texts in sooooo much detail that is required of you (remember it's often quality over quantity).
So, for me, I suggest studying only the text that you would be doing on the Close Analysis SAC (you would have practiced/prepared on that as you would or the exam- hopefully :p) and another one you are comfortable with leading up to exams!
Also, I would advise you not to do poetry UNLESS you are really capable student (mid-high A+s); read the John Keats poetry close analysis on 2011 VCAA paper to see the quality required to do poetry and get in the high-scoring range! Doing poetry is a blessing if done well, but a killer if not! Don't be fooled that it's shorter to read than novels, etc expect to study up on literary techniques specific to poetry (e.g. Iambic pentameter) It's a risk to do poetry!
That said, if you see my other posts on the Lit forum I always emphasise that these are only my opinions and I always encourage to do what feels right for you!
