If you plan on getting a new iOS app approved or want to submit an update before the end of 2015 you better do it soon as Apple will not be accepting new app or app update submissions from December 22-29. Other typical iTunes Connect and developer account functionality will remain available.
That basically means if you plan an app release before the end of the year you have through Monday to get it submitted, approved, and scheduled. Apple will start back the app submission operations on December 30.