>>344404652
I would say what an average learner should learn is something like:

1. Hiragana
2. Katakana
3. Basic particles (は、 が 、に、etc...)
4. Verbs and how to use them
5. Sentence structure < ---- THE CLASS IS ABOUT HERE
6. Start learning more vocabulary, basic sentences, grow your knowledge

People of all skill levels are good to join, but the overall skill level of the class is past hiragana, katakana, and at least knows kinda how particles work. If you learn all that, you can join and feel fine about where you're at. If you know more, that's great and you can help other confused anons and feel confident in being good with where the rest of the class is going.