Is there a planner to estimate dates of completion using lesson numbers?

I second @Kraits’ Level Projection recommendation for getting your projection

The other thing to keep in mind is that levelling up depends entirely on getting to Guru for the level’s kanji. So if you wanna level up faster, you might want to prioritize doing the radical+kanji lessons first and then start the vocab as you’re reviewing them. In case you’re not using it already, there’s a super-useful script that lets you do just that: [Userscript] WaniKani Lesson Filter