Mostly the app is visible in the iTunes App Store (on the PC, NOT on the iPhone) before on the iPhone. If it takes longer than 24 hours, I would consider contacting Apple but before you have an answer from them your app will probably be Live so... Just be patient, it can take some hours... But again, check iTunes on your Mac/PC if you can find your app there, in my case it was always like that, first iTunes then App Store.