It really does depend on the kind of topic that you are teaching.

As others have stated here, it could be as little an hour to as long as a few days.

There is, however, a framework that I use to speed things up a bit and put probability a bit more in my favor when it comes to helping my potential reader to understand better what I'm trying to explain.

I share some tips on the ways in which you may do this here: https://fromtoschool.com/why-most-programming-tutorials-are-....