Yes, I know this switch you are talking about... but IMO is better to do this procedure:

1) do some half throttle horizontal circuits at a safe height, with the gear lowered to bleed off the plane speed.

2) when the plane is flying upwind, over the runway (still at a safe height) lower
the flap. and keep the finger in the switch. if a violent reaction happens flip the switch back and don´t use them at landing. (of course, LOL) Later mix some elevator compensation and try again until there is no great pitch change... however if at the first try there is a mild pitch variation, use the elevator trim to compensate it and land this way, and later dial this elevator adjustment in the mix. also remember that the trim pitch varies with the plane´s speed. even if you are using mixing on the flaps.

I always liked this procedure because if something wrong happens with the flap deployment, it
allows a quick restore of the flight trim condition (even if the pilot panics) and the plane has plenty of height to recover from any unusual atittude.