The Master List of Book Clubs is probably the best place to find out about all the upcoming books.
The book clubs names are a bit odd because the Beginner club originally split off from what is now the Intermediate club - so it was definitely beginner in comparison! - and then the Absolute Beginner club was created to read even easier material aimed more at young children.
You can’t really start reading before you’ve learnt any grammar though. I’d also say that grammar is probably more crucial than vocabulary, as the latter is easy to look up.
So, Absolute Beginner is probably aimed at around N5 level learners, although native material does not align with JLPT material and thus you are always going to encounter unknown grammar. If you feel like you wouldn’t be able to manage that (note that they don’t read the material very fast, and of course you have all the help of your peers), I’d recommend checking out something like graded readers first, or things like assisted readers.
There is a graded reader book club to give you some ideas and support there, and there is a reading resources thread which has lots of link to different options, including some free.