When I stop at the store (see above), I press the Park button,, then release the brake, noting the very slight movement as the drive train takes up the slack as the parking pawl stops the movement. It's quite distinct, if you're looking for it.
I find it hard to see the dash display at a glance, it's blocked by the steering wheel and the extra cable going to the LeafDD (AKA "Gid Meter") that I wrapped around the column.
I agree with the others, the O.P. needs to forget his piano playing and perform a firm, deliberate press of the button.