It does make sense to join the Absolute Beginner Book Club now - it will reinforce what you learned in Genki I and complement your Genki II studies as you work through both the text and the book club book at the same time.
I speak from experience. It wasn’t until my third attempt at joining a book club that I was comfortable, by which point I was about where you are now. Everyone is very helpful with great questions and answers, a vocab list, so you’re definitely not going it alone.
You can check out the ABBC here and see the links to current and previous book groups. Hope to bump into you in one of the threads in the near future (I’ll be joining the わんわん探偵団 book 2 thread in January).