When is this 2 month period? 2 months beginning right now? 2 months beginning in a few months? Beginning in a year?
If it is immediate, I personally would do it. He's not asking you to wait indefinitely to date, he's asking you to wait until he is in a position to emotionally handle the strain that the adjustment takes. While he's studying, he is NOT going to be able to process relationship changes in a healthy way AND be able to absorb and prepare for the exam like he will need to.
If it is way down the road, then I would ask for a compromise. Maybe a minor DADT kind of arrangement where you can date casually but not form any really lasting commitments until he is able to discuss (after his exam).
Opening up a relationship is a major life change - especially when you're monogamous in nature. Taking an exam that is going to forever impact your career, life goals, etc - also a major life change. I don't do more than one major life change at a time (if it's within my control). Someone trying to force me into more than one major life change is not someone respecting me. You have to respect that this exam is a big deal and that he needs to be able to focus. You dating could very easily compromise that focus in a way that could cost him dearly. What's 2 more months of waiting, researching, and thinking about what you want to look for when you're able?