So when does this start ?
Astronomical Spring starts March 20th at 15:33 to be precise, well for Bristol, UK it is and maybe a few minutes give and take where you live.
Metrologist I believe go on the 1st of March for the first day of Spring.
So if you qualify for NCB on the 20th March 2023 you may or may not get the higher payment according to the time of day on that day.?