I'd file a small flat on one side, put the flat side down and file another flat on top - Can be smaller than the drill bit, but gives you a good spot to start and makes it easy to find the two opposite sides.
Use an awl to make a starter hole, then drill half way + a little bit from one side, finish off the hole from the other.
You've got a lot more tolerance for error if you meet in the middle, and can also clean up the join with a file if need be (if you have a small enough file at least).