i would say start right away. that’s what i did.
I don’t claim this is the best way, but from my experience getting to at least level 10 really helps. Being able to recognize some kanji in the vocab you are learning (and yes there is alot more vocab you should really learn in the textbook) really helps with retention. Doing it blind without that would just be a confusing mess in my opinion.
The official Wanikani recommedation is to start grammar BY wanikani level 10 NOT AT level 10. So many people make that mistake.
I recommend you start as soon as you can! I waited until level 10 and was very frustrated by how some textbooks lack of kanji, which made it harder for me personally. Doing grammar, vocab, and kanji at the same time helps level your learning.
There is no one fits all, but here’s the resources I’ve used: Genki 1 (currently working through Genki 2) really helped me learn a lot of grammar and practice. I sued the textbook problems and the workbook. I mostly used the workbook as a review to get some SRS system going.
I also used BunPro a little. It’s really helpful, but I often don’t have time or access to a computer to use BunPro often (and I like learning kanji so I always start with WK when I do have time/access to a computer )
I also bother people who speak Japanese to practice with me Usually it’s my poor fiance
Here’s a thread with a bunch of Japanese resources you can look through
I would recommend to start grammar as soon as possible. Otherwise, you will reach level 10 and be able to read words but won´t understand anything because of grammar. Once or twice a week should be fine and you can adjust with time (when you read if you have a hard time reading words then focus on Wanikani and vocab in general, if you can read but don´t understand what you are reading then you need to study grammar).
Enjoy your journey.
That’s almost certainly more grammar knowledge than me. While I agree with your sentiment, being able to pick up on “the very basics” would be helpful.
I have both Japanese Sentence Patterns for Effective Communication and Basic Connections, and I got to say that Japanese Sentence Patters is more beginner friendly because it starts from the very beginning, while Basic Connections requires prior knowledge of Japanese grammar.
But I would suggest starting with a more holistic grammar source that also includes stuff about culture and example conversations like Human Japanese or japanesepod101
I pretty much second this, but would add that it’s helpful to get some english language explanations of the structure of Japanese sentences and some basic knowledge of common particles first as a toehold.
Also, there’s an Anki deck “8547 Japanese Sentences from the 日本語文法辞典” which I found (well, am still finding, 8547 is a lot of cards…) very useful. Yes, it’s SRS, but you can just ignore the pass / fail side of it and use it to present you with a set of sentences to read every day.