Practice, practice, practice.
Seriously, it's just a matter of time and exposure. Eventually your brain does the flip and it becomes easy. Sit at home and just view the kitchen, practicing. Deliberately pan left and right as if following something moving is really helpful to make clear what the reversal is about. Think about the camera as a pivot point, the center of rotation, and pay attention to which direction you need to turn to follow something moving from one side to the other. Once this gets ingrained, making the flip gets easy down the road, but it takes time for the brain and muscles to get a handle on it. I can not use a waist level finder for weeks or months, pick one up, and be comfortable to the reversal within 30 seconds, but that's after years with TLRs.
You can also do this practicing without the finder in place, viewing just the bare screen. this can help make the adjustment easier as you aren't trapped inside a pipe while dealing with the direction issue.