Migrating from 2.6.x to 3.4.x

Have production meteor app in 2.6.x with android app (several apps pointing to the same app - changes layout based on customer). The app is used by some 5000 users. After several tries was able to use Claude to migrate to 3.x ( had huge problem with packages and global variables) and to 3.4.1 surprisingly with no problem ( though others have reported it). And was able to build Android app with some minor tweaks. Wanted some advice for rolling out the new version to prod, knowing well the android app upgrade process takes time and folks may not move to new app quickly. What would be the best wa