While you'll be able to start learning and using Kotlin on its own, you won't be able to escape having to pick up some information about Java along the way, esp

While you'll be able to start learning and using Kotlin on its own, you won't be able to escape having to pick up some information about Java along the way, especially as you dive deeper into the language or make more use of Kotlin's features. You'll also be wanting to use Java library at some point whose documentation is in Java, so you'll also have to be able to 'mentally translate' the documentation. One of the things you'll have to get accustomed to in Java as opposed to C# is just how many libraries you'll be importing, for features where the language itself either doesn't provide anything or provides a poor implementation.