And on the Dash 8...
The captain tells the first officer out of which exits should the evacuation be performed; he starts and completes the memo items and I relay the information from the captain to the (single) lady back there by any means (PA or visual). After that, I do my flow, go out the cockpit and assist the F/A in the evacuation and actually, the first officer is the first crew member out of the airplane to assist the pax while they're sprinting out of it. Flight attendant and captain evacuate the airplane through "the most convenient exit" according to my SOP.