2 covers are not enough. Aim for two that you can alternate throughout the day and 2 that are in the wash (if you wash every day). Newborns also have a sneaky habit of doing very runny explosive poos (so called poo-splosions), so you need to allow for a cover to get soiled every now and then (or more, depending on the baby).

12 prefolds: Again, depending on how often you are planning to wash. In theory you need 6-8 a day. One lot in use, one in the wash, so 12-18 nappies). In reality, I rarely used more than 6 a day. But I still think you might be cutting it a little fine. If you leave your washing a little late cause you're not ultra organised that day (ie. sleep deprived, sick bubba etc.) or if your washing gets rained on you might run out. I'd get a few more for backup. Even if that's just the cheap terries from Woolies.

That's just my 2 cents...