Before I talk about my personal experience, here is a caveat: everyone works at different paces, and one of the cool things about WaniKani is that you can figure out your own pace. Use the early (and easier) levels to figure out what your pace is, and adjust your WaniKani experience to it. It involves a bit of trial and error but, assuming you are dedicated, a bit of trial and error in the first 10 levels makes the next 40 levels much better.
For early levels, where I knew many of the kanji already, I would do all of the available lessons as soon as possible. This was very hard and resulted in an uneven WaniKani schedule (i’d have 2-3 days of 200+ reviews, and then a few days of practically nothing).
After I caught up with what I knew, I picked a number of Apprentice items I was comfortable with, and did lessons whenever I was below that. For a while I chose 100 items, but now that I am further in and am trying to focus on non-WaniKani study tools, I keep it at ~50. The idea behind this was that Apprentice Items are the items I will review AT LEAST every day, so with 100 Apprentice Items I have 100+ reviews every day. Now I have 50+ reviews every day (usually in the 70-120 range), etc.
With my method, WaniKani is slower than a lot of other people’s, but it works for me and I haven’t grown tired of using WaniKani in my multiple years here.