The avalanche transceiver should be switched on in the morning before you put your skis on!
You must check the battery life, change the batteries if necessary and conduct an avalanche transceiver check. One of the members of the group goes into search mode and makes sure that they are receiving the signals sent from all the transceivers in the group.
The purpose of this is to:
1/ make sure that everyone has remembered to switch on their transceiver
2/ verify that all the transceivers are correctly emitting a signal