When is an updated app downloadable from the App Store on the iPhone and iPad? Example: Pokemon Go 0.83 was available yesterday around noon (Nov 27, 2017), and one of the person in our group downloaded it around noon. 

But I checked and checked, even restarted the App Store app, rebooted the iPhone, and could not see the Update button. Not until about 10 or 11pm.

And today I wanted to see how the app looks like on the iPhone X, and again, I restarted the App Store app, and rebooted the iPhone X, and there is still no Update button, when it is 5pm and 28 hours after somebody was able to update it.

When is it supposed to be available and is there a way to force the update to show up?
This is one way you can try, not guaranteed to work but it might:


  Delete your app, and then just install it again


the App Store app / server might decide it would waste too much bandwidth to let you download the old version and then update you within a day or two, so it will just give you the latest version.