The general process I use is to install the wiper arms last. I install the motor and make sure the piston and driving pins are in the parked position. Then I connected the wiper arms without moving those parts on the motor.
I then operate the motor with the connected linkage for a few cycles with the engine vacuum and turn the motor off. This confirms that everything is in the parked position.
Then I go install the wiper arms with blades in the desired parked position on the windshield. Normally this is as low as you can install them while they are pointing to the center and still have the blades resting on the glass.
Due to wear in the pivot pins and transmission chains you might have to reposition the arms one or two serrations after everything has been cycled under load. I do spray water on the windshield when I am doing this process. The extra friction of the blades on a dry windshield reduces the travel of the arms.
