We are submitting an app to the App Store this week with a predefined release date (lets say its the 15. of December 2012).
Lets presume, that the app is approved. If we (after the approval) post an update (hypothetically on the 10th of December), would the app still launch on the 15. of December (without the update) or will the whole release date be pushed back until the update is approved?
Any info will be appreciated.
The app will launch with whichever version is currently approved for sale by Apple. If the approval has happened of your new version, then it will be released. Otherwise, the older version will.
It is worth noting that Apple does not review apps for a period of time over the holiday period.
Hope this answers your question.