Jetbrains has been using Kotlin in house since at least 2011. At my company we started using Kotlin when it turned 1.0 in Feb 2016. It's been a huge success with programmer productivity and happiness. Currently have 18000+ lines of Kotlin in production. Whenever given the chance we refactor large Java classes that are 1500ish lines to 300ish lines of Kotlin.

Compared with switching from Obj-C to Swift, the transition was relatively seamless. No bridging header for interop with Java. Also Android Studio/IntelliJ has very mature language support for Kotlin that should keep most IDE driven developers happy.

How so ? It was premature 2 years ago but kotlin is pretty much mature on Android right now.

No the timing is perfect.

It will be on their resumes exactly when companies start looking for kotlin talent.

What ?! Do you have any experience in android development? Remember that everyone is till stuck in a null filled java 6 feature hell. And don't come at me with half ass backported lambda expressions and no real java 8 features.

I wouldn't go back, EVER