I think this can vary a bit depending on whether you’re doing SRS elsewhere (I guess you’re also going through WK), how much time you have, etc.
My suggestion would be to avoid starting too many decks for now. Maybe just go with one. If you’re using Genki to study, you can take the opportunity to use the Genki Vocabulary Deck, or if you’re just looking to learn common vocabulary, you can study the Core 10000 words. Since you seem to be doing Wanikani, Core 10 has these tags L1, L2, L3, etc which represent the WK level at which you’ll be able to read that word So that might be definitely useful.
Also, start with a lower amount of lessons. Maybe just go with 5 a day and see how you do. If you feel like later to can do more, you’ll just need to adjust a bit I think it’s always better to aim for fewer lessons a day that you can actually do than overdoing, losing consistency, and feeling stressed about this whole thing.
Hope it helps!