I was just going to tweet this, but then I realized that it'd be a little over 140 characters.
I've noticed a lot of my developer friends lately don't even know this. So, if you're an iOS developer, plan to be, or are marketing for an app that's coming out soon, you'll want to read this.
Being in the app press biz for over three years now, I know my ins and outs of covering apps as news and reviews. This includes dealing with promo codes...a lot. Sure, we do beta tests through Hockeyapp and Testflight, but in the end we always need a promo code of the official version of the app.
Luckily, Apple does this awesome thing—though they don't seem to let you know about it for whatever reason: They allow you to set a release date for your app when you submit it for review. Instead of choosing for it to go live on the App Store upon Apple's approval, you can pick a release date far into the future. Whatever date you want; and you can always change it later. Then, once your app is approved by Apple, you have early access to promo codes.
This is awesome for you on three levels.
1) It allows you to have full control over when exactly your app will be released. Which is amazing because if you've ever submitted an app with Apple you know waiting for it to be approved so you know when it will go live is an excruciating process.
2) This helps you get maximum press exposure, as you can share these promo codes with the media early and get your app previewed (if you allow that, if not be sure you give the press a specific embargo date and time) and/or reviewed the exact day it's released—and we (the media) LOVE early access. I definitely appreciate the heads up, too.
3) This also seems to give Apple extra time to check your app out and decide if they want to feature it. And surely you don't want pass up that opportunity.
Keep in mind, these promo codes allow full access to your app. The person given the promo code will download it from the App Store just as if it were live already—but it's not. Only the person with the promo can use the app and check it out.
One last thing: Yes, you can even get early promo codes for apps that will be free. This allows us to check out your app before it's released, just like any other paid app.
Just wanted to share this little tip with the iOS community as I've noticed few, if any, developers I speak to know this is the case. And folks that do PR for apps are left in the dark too.
Stay tuned for more free marketing advice! (Someone should pay me for this shit.)
UPDATE: Another great promo code tip. Thanks, @Chounard!