It doesn't matter much in my opinion if you start with Scala 2 now or wait for Scala 3. Scala 3 is 95-99% compatible with Scala 2. There is very little that you would learn in Scala 2, especially as a beginner, that will be truly obsolete when 3 is out (an exception might be symbols, which had very little use anyway). In addition, most existing codebases are in Scala 2 at this time.

(I, and my company, use Scala as a general-purpose language, targeting both the JVM and JavaScript, by the way.)