With a working washer bottle it seems rude not to fit the wiper arms and blades.
I can’t remember where I read this, but I am sure I have read about the need to round off the corners of the wiper blades for IVA. It’s not much, just so there are no sharp edges. I used a file and a little black paint to make them look neat.
The next part of the process is to make sure that the wiper motor is parked, and to check which direct it’s going. Caterham actually have the wipers going the wrong way, they sweep towards the passenger. I checked the wipers were parked and the direction on travel several times, before committing to press the wiper arms onto the spindles. The arms should rest just above the windscreen frame. The wiper blades are also just a press-fit to the wiper arms. If you do get the arm in the wrong place, lever it off very carefully (with a plastic trim lever if you have one), because it’s very easy to slip and damage paint.