I keep coming back to the meaning of sen.

/sen/
awareness; anticipation; readiness to act

It’s not that I’m overly forgetful but it’s useful to review.

Sente. “First move , initiative ”, abbreviated as sen. The idea of sen is that one is“ready to act”. 

An essay I found by Stephen Quinlan from 2011.

From sen we get the mitsu no sen:

• sen no sen – I strike you as you begin your attack
• go no sen – I strike you while you are attacking me
• sen sen no sen – I strike you just before you begin your attack

One of the references I find most useful is this one from George McCall back from September 2015.

I think this is worth reviewing over and over.