You can go either direction but I did it in this order.

1. Changed the fluid.
2. Go for test drive to make sure all is good
3. Install the RedHead
4. Top off fluid after the change.
5. Turn on vehicle and move steering left to right and check fluids.
6. Take test drive and check fluids - it may be noisy for a bit but should go away if fluids are good

You will not loose that much fluid when you change out the steering pump but it will require more.

Tim M