I’ve also always found the advice to wait to be… difficult to understand. Especially given how slow the first few levels are.
That advice has always felt like its putting WK/Kanji on a pedestal which I don’t think is particularly deserved/helpful, Kanji is important for reading and eventual fluency, but I’m not convinced it should be the first thing you learn. Knowing a few hundred Kanji but not being able to form the sentences “Good evening, how are you?” or “I like apples” seems like it could kill motivation.
I definitely didn’t put everything on hold until I got to a certain WK level, I kept learning from other sources, kept up with my Anki, and made sure to prioritise WK to an extent but only because it was working for me and it was relevant to my goals (reading).
Obviously you should be careful to not burn yourself out, but picking one resource to go through alongside WK doesn’t seem like it comes with a high risk of burn out. Just keep an eye out for if things get too hectic, and if that happens then you’ll need to reprioritise (based on your goals).
[sorry for double post, just wanted to keep my on-topic reply separate from off-topic]