MD is different. The cycle is more condensed and applying early gives you a pretty big advantage. The general rule of thumb is you're not late for MD until Labor Day, but you're also not doing yourself any favors applying in August. Keep in mind secondaries take a long time to fill out - doing them on a time crunch is tough. But depending on the rest of your app, the state you live in etc, it may not be a deal breaker. Impossible to say though.
So my advice would be to just see how the test goes. If you do well apply to DO schools that interest you. If you do really well than you could apply both or consider padding your app for an early MD cycle next year.
Applying now puts you in a tough position if your score doesn't turn out the way you want to. That's why I would recommend waiting. There's a lot to be said for applying once, early and with the best application that you can put together.
