Count on a couple of hours or more, depending on which route and road conditions, and the vehicle you are driving.
I haven't been there recently, but latest reports I got, are that the road is still laden with potholes.
You head westbound to Puerto Plata, on through, (Route 5) heading to Santiago.
A mile or so after Imbert, there is a right hand turn in the sugar cane fields, indicating Guananico, turn in there (route 218) and pass Guananico to Los Hidalgos, left turn to Punta Rusia from there.
Alternately, you could pass Imbert and get onto Highway 1, westbound at Navarete towards Monte Christi, then Northbound at villa Elisa to Punta Rusia.
I don't know which is faster, nor which has the worst roads.
Perhaps Chris can enlighten you more.
Email me if you need a map.