Identifying location and severity of fire!?
Criticism of the flight crew and cabin staff is probably premature. In such circumstances it may not be certain, at the time that evacuation is ordered, either the location or severity of a fire. This is particularly true when the aircraft is engulfed in smoke. The timeline of the decisions needs to be considered, but it all seems to have been appropriate and effective under the circumstances.
From reports, it seems that the cabin staff properly evaluated the situation once the escape doors were open (if not before) and directed the passengers accordingly. This was not a drill. No doubt there may have been areas that could have been handled better and that will be investigated.
The priority was to remove the passengers expeditiously. The situation could have become very ugly, very quickly. Fortunately, the timely and effective response of the fire services averted a catastrophe, together with the prompt effective action of all others involved.