They come from Gödel's Philosophical Notebooks, specifically volume two which is about time management (https://www.degruyter.com/document/doi/10.1515/9783110686586...).
Notebooks provide fascinating insight into how Gödel dealt with issues of focus, productivity, producing meaningful work, dealing with distractions and similar topics Cal and many others often talk about.
These notebooks are from 1934 to 1955, the period in which he struggled to produce impactful work after incompleteness theorems.