A fourth option is to submit the app in advance, but release it to the store at a later time. On release date of the iPad, get one, drive home, test your app, and if it's running well enough, put it online in the store.
That's only an option if it's a separate iPad app. I guess a lot (most?) iPad apps, especially just after launch, will be existing iPhone apps with some UI tweaks. You can't take an update offline in the appstore without completely removing your app (you can only have one version).
