The Fennwick stairs are all within a mile of each other, which makes the map order look sensible and feel terrible. Taken north to south you gain almost all the height in the first twenty minutes and then walk downhill for two hours.
The order I am proposing spreads the climbing across the whole route by zigzagging the slope. It adds about half a mile and takes roughly the same time, because nobody has to stop.
If you know these stairs better than I do, tell me now rather than on the day.