The date has nothing to do with the weather.
Weekend of 2nd- I am not available
Weekend of 9th is HPM weekend
Weekend of 16 th is to close to HPM- it will upset the locals if there are
2 big events on consecutive weekends
Weekend of 23rd is Easter weekend- it is busy enough in Edale that weekend without the Skyline as well- plus I usually go away then to avoid the crowds.
Hence that leaves the 30th.