I asked this while I was a co-op student and all the analysts recommended waiting until you're a full time employee before doing OC1/2 because they cost about $1000 to register (full time employees get reimbursed for OCs but co-ops don't). Also, at least at my company, the raise for OCs is around 1% whereas exams around 5% or higher, so focusing on exams might be your best best.