This is extremely similar to the 'microscopic planner for shell' that I wrote and often use.

Take a look at https://news.ycombinator.com/item?id=14126006

I also add a few aliases to make it even quicker:

  alias mcr='mplan create'
  alias msh='mplan show'
  alias mrm='mplan remove'
  alias mclear='mplan remove \*'

This will provide (in my opinion) both a very simple way to take notes and a somewhat mature and usable note taking 'program'.