I have a similar set of VHF instructions stuck – visibly – beside the radio, but I’ve also included (after the bit about switching the radio ON)
Turn UP the volume to 3/4
Turn DOWN the squelch till a very loud hiss is heard, then slowly turn the squelch the other way till the loud hiss just about stops
This is to ensure that in any fuss the squelch hasn’t been accidentally turned up and INCREASED, so that any response to a Mayday – or other signal – is not heard on the boat.