You can do all of them at the same time after getting the initial momentum, however not overloading the cognitive capacity is important. Otherwise the process may backfire.

The most important point is not forcing yourself to progress, but integrating the language in your life. A foreign language is not an achievement, but a capability (or ability), like programming in another language. You need to integrate into your life, not achieve and set aside. So not forcing is much more healthy IMHO.