Reset on ME's

I’m evaluating one of these against the competition - I need to commit to PCB within about a week.

Is it necessary to reset the device after power up?
How long does reset have to be?

Resetting allegedly takes 30-60 seconds (ref: the distributors), but the two flashes on the Green led do not seem to relate to the end of this process, nor is there any detail about this in the manual.