Tricky one!
In my experience, CC were authorised to initiate an evacuation without a command from the captain or FO in a CATASTROPHIC situation.
In their particular circumstances, whether or not a smell of smoke/burning with no obvious evidence of fire constitutes a catastrophic situation - well??
(p.s. Crossed with CP)
Edited to say that I would not wish to discourage CC from using their initiative in a life-threatening situation.