For starters, I don't think there is such a thing as perfect code. You're always going to discover (and hopefully squash) bugs along the way. Apple might roll out an update for iOS and complicate things. Perfection will always be just out of your reach. That being said, I keep a dedicated QA tester on call to ferret out all known bugs and quirks. We test and iterate until the app is as perfect as it can be. Only after my tester has performed regression testing and verified that all known bugs have been fixed do we submit the app for review. Then, once it's in the hands of real people using real devices, I can learn how good a job we've done. They tell me what they want or what doesn't make sense. You'll always want to release regular updates—if only because it's good for your marketing—and you'll want to save development dollars for future development phases during which you add significantly to the codebase. So for your first project, I wouldn't let your developers' eagerness influence the timeline. Only submit for review after you're confident that the current version of the app works flawlessly, but keep in mind that you'll have plenty of time to make more changes. And hopefully, your new revenues will pay for those changes!

Cheers,
Austin