Hm, it could even coincide with Earth Day on April 22 (either on sendouts or crafting) . . . although I've heard that in other places around the world, Earth Day is a different day? (I'm in Canada, and I know the US does April 22).
It looks like Earth Day 4/22 is pretty global, although some also celebrate on equinoxes. One thing to consider is that Easter is also that weekend in the U.S. Not sure if that is better (more time off for some) or worse (busy with family events).