There is video of a Cirrus parachuting into the Pacific.
Touchdown at 1m 51s (44:00 on clock?)
In a few seconds the water on the RHS door was up to the windows due to the parachute dragging the aircraft.
The sole occupant exited the LHS and the aircraft was inverted and the cabin full of water at 2m 26s (45:06 on clock?).
It appears that therefore it was 65s to invert the aircraft and fill the cabin with water. I suspect that it would have been MUCH sooner if the leeward door had been opened instead of the windward door. I would presume that there was no way that the pilot could control the way the aircraft was pointing at touchdown.
Maybe Cirrus could improve the water landing performance in a bit of breeze? I can't really see how 4 people could have escaped.