As we all know, the equinox is March 21/22nd.
But I bet you didn't realise that sunrise and sunset will actually be 12 hours apart, not on the equinox but on March 16/17th
That is because sunrise and sunset are measured when the first or last glimpse of the sun's rim appear over the horizon. The equinox applies when the centre of the sun is exactly halfway up or halfway down on the horizon, some 4/5 days later.
Yes, I only realized that a few years ago, since I have to keep track of sunrise and sunset times to get the best lighting and effect for my events. Here on Kaua'i, it is today March 14th, the 12 hour apart event happens. This morning sunrise was at 6:45am and sunset will be at 6:45pm.