You should get an idea here. (heh, the thread isn’t locked yet.)
I was a speed runner, but not only WaniKani. I also did Anki alongside, and whatever other resources I had found. (That time, I dealt with leeches with mnemonics.)
Currently, I take within 2 weeks per level, but I don’t make that many mistakes. I put leeches in Anki sometimes, because I have a nice Yomichan.