>>344404652
You don't really need to catch up on anything just stop in whenever you feel like. Skill level is all over the map and there are no structured lessons, just different talks from anons.
If you want though that video I linked to is a pretty nice beginner series that some of us are going through together. I'd recommend giving the first few a watch and you can go through the rest in time.
Also if you're curious the og post has some summaries of things shown so far in the hackmd's.