The equinoxes and solstices are 'season cross-over' times:
the Spring/Vernal Equinox (about March 21) the Summer Solstice (about June 21) the Autumnal Equinox (about September 22) and the Winter Solstice (about December 22)
On the day that a new season begins, make a wish after the official 'cross-over' time, while crossing your fingers. The closer to the exact time, the better the chance of your wish coming true.