Should I take the Chemistry Subject Test after advanced chem (May 2016) or after IB SL Chem (2017)?

Should I just get it over with this school year as a sophomore or have some more general reinforcement and wait until next year? My teacher this year is pretty good and she teaches mostly everything on the test (she’s also the Chem SL teacher), but I’ve heard of people taking AP Chem and still getting low scores. I’d want a 750 or above, and I’d be willing to work for it; but for those of you who know, how useful will Chem SL be, if at all? Thanks!

I would take it after the AP, not the IB. IB covers weird material, and my hunch is the AP Chemistry class is more aligned with the SAT Chemistry test. Both will prepare you well, but as an added bonus, taking it after AP will relieve the testing crunch your junior year.