Cordova / Phonegap downloading a lot of images, best possible solution

I need some advice. I have Phonegap / Cordova content app created using Ionic Framework. This app is supose to work both offline and online.

So far I managed to implement offline database (SQLite), but I have some trouble with images.

The first strategy I chose was to "install" all the images at the beginning of first start of app (in meanwhile Progress Bar was visible)

It works, but I think that first start of app is simply too slow (it's over 800 images) It takes more than 7 minutes, which is really bad for user experience.

Here are some of my strategies:

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  Download all the images as single ZIP file and extract it into device

  
  


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  Download only some part of images (25% ?) and then download rest of them in the background, while user can use his app. Use some kind of images placeholder at some places ?

  
  

Which strategy is the best ? Maybe someone has similar experience ?