Start learning Japanese grammar

I would personally suggest starting as soon as possible so what you learn starts making sense and you can “play” with the language. I started learning Japanese in a classroom setting using the textbook Minna no Nihongo, but it may be challenging without a teacher, although it has a side book for translations and grammar notes which is very helpful. Another very popular textbook for self-taught learners seems to be Genki; I checked it back then and it seemed nice, I remember myself liking it, and I think there are some YouTube channels going through the chapters which is nice. Both Minna no Nihongo and Genki have listening practice too.

Another popular option is Tae Kim’s Grammar Guide, but I haven’t used it so I can’t say anything about it. Some people like it, some people don’t, but it’s free so it can’t hurt to try it.

For Kanji practice other than WK, if you use an android phone I highly recommend the app Kanji Study. It is a paid one but it’s constantly being developed, and I’ve used it for hundreds of hours over the years.

Some people dislike textbooks or grammar-heavy resources a lot, but they tend to be very effective, challenging you with listening, reading and writing; at least they have been for me. They can be tedious, but they get the job done. I tried to find the easy option at times, but I’ve never learned as much personally without putting in the work.

My last recommendation is to check the Ultimate Resource List even if out of curiosity, you might find things that you like and work well with your learning style.