I remember when I first tried reading a comic book in Japanese. I struggled on the first two pages, and gave up. A couple years later, I tried with an easier manga, and failed again. Each time, I didn’t follow up by doing the things required to be able to read a manga.
Your basic requirements for reading a book or manga with furigana will be: 1) learn vocabulary, and 2) learn grammar. And if the book lacks furigana, then 3) learn kanji.
WaniKani teaches vocabulary to reinforce kanji. It isn’t going to give you all the common vocabulary, so you need to learn common words outside of WaniKani.
Anki has a “Core 2000” deck. Starting with this deck today will help gives you a foundation of the most common Japanese words. You don’t need to learn 2,000 words before you can read, but you want to be constantly learning and reviewing new words.
By the way, in learning common vocabulary, you will be learning words with kanji you don’t know yet. It’s simply the nature of the beast.
You mention that you’re using Bunpro, which will help you learn the basics that you’ll see often. By the time you complete the “N5” grammar in Bunpro, you should be able to recognize and understand the basic structure of many sentences, even if you have no idea what the sentence is saying.
Last year, a year and a half after I started learning common vocabulary words, I decided to read a volume of a manga, and not give up. Every time I encountered grammar I didn’t know (which was a lot in the beginning!), I researched it thoroughly and learned from it. I completed a 100-page manga volume in about six to eight months, and from it I learned more Japanese grammar than I had in the prior 20(!) years.
This is where the book clubs here in the WaniKani Community shine. You can ask questions about grammar you don’t know, and you can read explanations given by others. It’s like a shortcut to learning grammar you encounter.
The first manga or book you read, a lot of common grammar will come up repeatedly, then the next manga or book you read, you’ll find that same common grammar showing up.
If you asked me on January 1st how many volumes I expected to read this year, I might have said, “Two would be nice, if I have the time, energy, and strength. So, probably just one. Maybe.”
But being so thorough with that manga I read last year gave me a strong foundation. Joining the WaniKani Community book clubs allowed me to build upon that. Thanks to those (and an always-growing base of vocabulary), I’ve read more manga volumes in 2019 than I can even believe.
I often encounter grammar I’ve learned and forgotten and have to learn again, and it sticks over time. But there’s always more grammar for me to learn. I’m always looking up vocabulary, even with over 3,000 words learned. It’s still a victory if I can go four dialogue balloons without having to look a word up.
Reading begets reading. The more you read, the more you get used to reading. The more you read, the easier reading becomes. The more you read, the more comfortable reading becomes. And you’ll be able to read even more.
I attempted to read manga and quit twice before. Each time, I didn’t follow up by doing the things required to be able to read a manga. Start learning common vocabulary and especially learn N5 and N4 grammar, and you’ll find level 0 readers to be easy to understand sooner than you expected.