Learned Something NEW about my Prius

Sorry I wasn't monitoring this past week or I would have replied your question immediately. But you tried and learned it yourself

I am glad it worked for you

 

You figured this out already but I will answer it for others to know.
It is exactly the way you said. Power it up with foot on brake. See the "READY" on display. Your 15 seconds has started (may not even be 15. Maybe 12 or so)
Do whatever you want (shift to Drive or Rear, move the vehicle etc.) and before the 15-second time is up, shift it to Neutral and the ICE will not start.

But you WON'T reset the 15-second time or WON'T be able to use the remaining of the 15 seconds (in case you shifted to Neutral say in 5 seconds which should theoretically leave you 10 more seconds). It still countdowns while you are in Neutral. It just doesn't start the ICE.

And one last thing and VERY important. You MUST power off the car by pressing the power button directly from the Neutral position. If you try to put it in Park and then power it off, you won't make it. Vehicle will start the ICE at the moment you shift it to Park.

Enjoy it

 

Totally understand...

 

And one more thing about the EV mode availability.
I was able to use the EV mode when the vehicle was cold but it is a hit or miss situation. I remember engaging the EV with 3 out of 8 bars left. But not being able to engage it 4 out of 8 bars left.

So it is like tossing a coin...