Lifetime is always $100 off around Christmas time.
Also whether you do monthly or annual depends on how committed you are to learning Japanese. If you ARE committed, then you should do the annual subscription hands down. If you’re still going strong by Christmas time then upgrade to lifetime. If you’re not sure if you can keep up, then do monthly for now and then switch to annual when you are sure.
Getting to level 60 within 400 days is achievable if you follow this guide which has you do your reviews three times per day at the same time every day. Otherwise, it takes most users 2-4 years. You should start studying grammar once you’re around level 10-20 and can read hiragana/katakana no problem.
Here’s a guide from the creators of WaniKani to learning Japanese.
Here’s where you can practice reading just hiragana/katakana
Here’s where you can learn Japanese grammar for free!
P.S. Your first two goals will take some time. At least half a year if you’re committed and can spend more than two hours everyday studying. Otherwise it may take one or two years. The main thing to watch out for is burnout. If you stick to a schedule, you’re more likely to succeed than if you go super saiyan from the getgo.