Best time to plant a tree was 10 years ago. Second best time is now. That applies with reading, too. (Basically, as early as it’s possible for you to read is the best time to start reading.)
You will almost certainly be lost at first, and that’s okay! Reading is a completely different beast than regular studying, whether that’s textbooks, SRS, apps, or whatever else, and it requires different skills, ones which you can only get through reading. Once you get started, it does get easier. And picking stories you like will make reading easier too, even if the content isn’t necessarily the easiest. For that matter, a lot of people find よつばと to be easy because of the relatively simple grammar and often not much goes on, so it is rather beginner-friendly, but others find it difficult because of the lack of kanji and even because it’s a slice of life and not much goes on.
I actually started out with reading a novel (a short story collection, to be more exact, of side stories to the light novel series my favorite anime is adapted from; and I started reading it 2 months before I started properly studying, though I did have some scattered prior knowledge. It’s been a year and both reading and studying have definitely gotten easier since then), and I found some manga I was interested in, but for some reason there was this mental block around starting it… and I also ended up starting with よつばと too lol. Though less because of everyone recommending it and more because I loved the series in English. And it was definitely nice when I could understand what Yotsuba was saying even with it all in kana, but there were definitely also times I needed to input it into the JP>ENG dictionary I was using to figure it out, and then like half the time it turned out I did actually know the word already lol
The next one I picked up was 舞台に咲け, and it was definitely above my level (much like that LN series…), and it didn’t help either that I wasn’t exactly used to the manga format while reading in Japanese, despite having read a few volumes of よつばと—they’re not exactly the same level. But I got through it after several days—I could never read more than a couple chapters of manga a day at most when I was starting out—even though I did get lost sometimes, yeah. Frequently, more like. Heck, I still get lost, a year and like 80 volumes of manga on, but I usually don’t get quite as lost, and it happens less often.
trunklayer linked the よつばと book club, and the book clubs on here are definitely a great place for vocab! They have vocab sheets put together by the participants, ordered by the order you’ll come across them and complete with definitions relevant to the context the words are used in in that instance. You can also ask questions and get an answer even in the old threads so you can be less lost than if you tried to read the book on your own. (Though if you did want to read a book there’s no club for on here, you can still ask questions on the forum and get answers. And/or suggest the book for the club you think it’s best suited for, and it might get picked!)
For vocab, aside from reading, I used to use Drops (I got frustrated with them putting out new topics that had few to no images, which are integral to how they teach vocab, but the vast majority of items do have an image and it is a good app. I probably will use it for other languages, just not for Japanese at this point), and I’ll periodically add vocab on KameSame, both that I’ve come across while reading and from one of their word lists. Many swear by Anki, and if it works for you, they’ve got many decks to choose from as well as the ability to make your own.