Here I had to get the vent duct into the soffit before installing the cabinets, and yet get the duct to line up with the hole in the cabinet not yet installed. The range hood comes with either 3-1/4 by 10 or 7" round. Problem is home stores don't sell 7" duct, they sell 6". They did however have a 7 to 6" round adapter which I put immediately above the range hood inside the cabinet.
Turns out the vent exited in an ideal location. Right in the corner under the protection of the roof. It also was in the wood trim rather than in the stucco, which is a bear to cut or drill.
It ended up being a tight fit. I had to hold the telephone lines out of the way with a large screw and the rain gutter required to be modified (beat a dent in with a hammer) to allow the flaps to open.