Now the actual app is ready. Check it using app test app (there are apps for checking apps). You can either publish it directly through your iTunes or Google Play app stores developer account or submit it to the site you used to build it. Now, wait and create buzz about your app. The marketing process you started from pre-production through research and continue with a blog and social media, now gets momentum. Make microsite for your app. Use promotional videos. Advertise on social media. Run some contest or other marketing tactics to gain attention. You should have a business model too.

Summary:
Recheck. Publish. Market your app.