[itsmejeff]

This may be a bit of a paradigm shift on the original question, but I’ve found that arranging my software and project in such a way that “cognitive overhead” is minimized will make startup cost extremely low.

If the code is very simple to reason about at a high level, you won’t need to remember many details. If your dev environment is stateless such that simply “opening the project” (for me, cd-ing into the project directory in my terminal) will automatically set up everything you need to start iteratively developing, you won’t have to focus mental energy on project setup.

This leaves you free to really only worry about the exact thing you were doing.