Timing myself as I go through the levels?

[Kumirei]

There is also this script

[Userscript] Level Duration 2.0

This is a third-party script/app and is not created by the WaniKani team. By using this, you understand that it can stop working at any time or be discontinued indefinitely. This script replaces the original Level Duration script. Unlike the previous one, this script fetches your level unlock date from the API, so it is much more accurate. To do this it relies on WKOF, so you will need to install that first for this to work. There are a couple of different display options for this …