[elliottcarlson]

"Some of the apps we discovered resided on Google Play for several years, but all were recently updated. It is unclear how long the malicious code existed inside the apps, hence the actual spread of the malware remains unknown."

If these apps were indeed popular, I would imagine the historical APK's are available for the various versions on pirate sites. Simply performing a Google search for "Fashion Judy: Snow Queen style apk" shows downloads for different versions of it. This can give a better idea of the length of infection.