Rwy in Sight,
The airline I work for state in the safety briefing that "Do not inflate your lifejacket until you leave the aircraft".
This counts for overwing exits as well as "normal" doors. If you should ever end up in a ditching situation (heaven forbid), do not head towards the rear of the aircraft. It's highly unlikely you'd be able to use the rear doors, due to how the aircraft is designed to float in such an event.
To clarify: Primary exits in a ditching is the overwing exits. Other exits may be used if the door is above the water line. Do not inflate your life jacket until you leave the aircraft, as in jumping out the door.
I can't at this moment in time remember the airline, but some years ago, there was a ditching where quite a few of the passengers who survived the impact drowned due to them inflating the life jacket inside the aircraft. The water came in quick, they floated to the top and couldn't get out. Someone might be able to put a link on here at some point.
Hope this helps.
Gg