The key to cooking ravioli so that it is firm but not hard and with the filling thoroughly cooked through, is to have a very large saucepan so that each piece has water around it as all the ravioli is plunged into furiously boiling water. The ravioli will float to the top.
The ideal time of cooking the ravioli is just under two minutes but more than one minute. Then have a slatted spoon to get the ravioli out thoroughly drained. It helps if the plate is warmed slightly, and any sauce you are serving is already to be placed on the table.