What should I do simultaneously to WK?

  1. Grammar is good to learn too. I found a textbook good, Genki is what I used, though people also seem to like Tae Kim and Minna No Nihongo, and Tae Kim is free.
  2. Day 1 might be a bit early to start it comfortably, but I think around level 10 you should consider trying some native material. The Absolute Beginners Book Club on this forum will help you get started. In about a month the book club will be starting its next book, Horimiya if you want to try join in on one live, or there’s the archive of threads from already completed clubs.