I would recommend against doing extra study of the kanji between reviews. Part of the theory of the SRS system that WK uses is that it tries to wait until just before you forget a kanji to show it to you again, with longer and longer intervals each time. If you keep studying the same kanji every day, then you will be interrupting the system and not getting the benefits that make SRS convenient over regular flashcards.
(edited out bad information about memory 
)
If you want to be conversational, you may want to add shadowing to practice speaking. It’s important to build muscle memory.
Other than that, you should indeed see a lot of results in 8 months. Be careful that SRS systems like WK and Anki have a progressive build up in intensity as items come back for review. So, as mentioned previously, beware of burnout! If you can avoid that problem, though, it sounds like a solid plan.
That’s not really how long term mermory work 
You can’t keep something from going to long term memory, only forget it before it actually does
I’ve never heard of this shadowing thing… is it as simple as talking at the same time as some Japanese person is?
I could 100% do that as I watch anime… it might be cool to end up sounding like Emilia from Re;Zero, or something 
Well, just repeating after they finished talking, but yes.
Resources made for shadowing will leave a blank so that you have time to repeat, but you can also pause the anime.
Try to use JP subtitles to check you understood correctly/are saying the right thing though.
(Also characters in anime tend to speak in exaggerated ways, so I’d be weary of that too)
Oh, that sounds like Pimsleur… but I’ll look more into it, thanks!!!
I don’t think you can do proper shadowing on your commute (that’s when you said you would use it), but yes, I think Pimsleur is a shadowing resource too
Pimsleur, wll probably get you to a mid/upper-beginner. If you want to take it farther, I would get Beginning Japanese 1&&2 (Yale Language Series) by Eleanor Harz Jorden.
This is chalk full of pattern drills meant to develop automaticity in your speech. This author actually made the basic course for the FSI (Foreign Service Institute). The institute was started during the Cold War to train diplomats for the U.S. Heads up, it’s slightly dated and romanized. It’s the authors own peculiar type of romanization.
Also, it doesn’t come with tapes. You have to get the audio portions from the Yale website.
**This is only for learning to speak
So, you are starting from Zero and are want to live in Japan by January next year for a short term.
What’s the goal? You want to order things at the Konbini. Explore the city having a basic understading, been able to move by yourself, etc… etc… persue learning a hobby? etc… etc… Start from there and then adjust, a year goes really quick, so if you are somewhat clear on your expectations you could have a better time adjusting the time you spend learning to improve at the things you expect to use.
Besides that, what you’ll be doing during those months? (probably the number one thing to consider). It’s winter in Japan… extra though for foreigners lost in translation …
Mostly I want to hang out in Akihabara and Harajuku, and find a hot Japanese boyfriend
Don’t know if you really need to speak Japanese to accomplish these goals…
It has already been said, but I don’t think learning (a lot) outside of the SRS is all that efficient.
Going for quantity over quality and then solidifying what you’ve learned out in the wild through reading is likely more efficient (and definitely more fun).
You seem really ambitious, not trying to drag you down, but going full speed for eight months is really hard. (not just with Japanese)
Burning out is a thing. If you feel like it’s getting too much, slow down. Trying to push through often just makes things worse.
I agree that maybe you shouldn’t study a ton of kanji all day. Things will bleed into each other and you will burn out very quickly! WaniKani will help you get the basic Kanji that you need down. Outside of WaniKani I would suggest that you at least learn the names of the places you’re visiting and how to read them in case you get lost.
I wonder if I can still get a refund on my lifetime… 
Probably a lot closer to “cringeworthy” than “cool” if we’re being honest. Like if someone came to the US talking like Buggs Bunny or Elmer Fudd.
I think there is such a thing as too much study, honestly. For me anyway I find that I learn the most if I have some downtime between active study sessions. Just the same as if I’m at work and trying to crack a difficult problem, sometimes it’s best to get up and walk away from it for a bit, and it’s like magic that you come back an hour later and the answer is obvious. Like your brain just needs time to subconsciously stew on things.
A few hours a day is certainly sustainable. 8-12 is not.
Having just gotten back from my first trip to Japan I can’t emphasize enough the need for listening practice and active vocabulary development. As others have mentioned, shadowing is great and I have found that Shadowing: Let’s Speak Japanese is very similar to the speed of conversation I heard over there.
For active development of your language skills - well, you have to use the language. An app like HelloTalk is really convenience for exchanging with native speakers.
(note: replying to op)
Yeah. Be careful shadowing anime. Unless you expect yourself to be screaming 「何やってんだ！」 everyday, then I would try to gain the ability to judge the “normality” of whatever you’re listening to.
Despite studying Japanese for 9 months, I’ve never actually spoken a single word of it to a real life person (I’ve interacted in Youtube comment sections though.) That’s because my priorities have been stuck to reading and comprehension.
Since your goal seems to align more with wanting to be conversational, you should definitely focus a ton on listening comprehension, which is why you might want to focus a little less on Wanikani and more on speaking and listening to people. Although, if you are super dedicated, you could find a good balance. Be extra careful about Kanji reliance, though. This is an actual issue I’ve had recently. It’s very easy to be 100% on Wanikani and completely forget that Kanji doesn’t actually exist in speech.
Suggestion: try a bit of immersion: change your computer, browser, Netflix, etc… to Japanese. Another point, as a general guiding principle, this article captured my heart: https://www.tofugu.com/japanese/quantity-not-quality-makes-fluent-japanese/
I think you need to add some speaking into this routine. I met a guy recently who spent a lot of time in Japanese VR chatrooms and was very ペラペラ (but also very 無礼). You could try something like that or for something a little less daunting iTalki or looking for a local japanese conversation meetup.
Shadowing is a great suggestion, something I don’t do enough of. I’d also recommend doing LingoDeer on the commute. It’s very cheap and a good complement to other grammar resources.
You may want to add some Japanese TV in there, allow me to spruik the list I am building of stuff that is on streaming services.
This is excellent advice. I’m slowing my WK right down so I have more time for things like iTalki (hit me up for an invite) and time with a tutor to get my conversational level up.