Hitting Galicia in May is fantastic, springtime with all the wildflowers, wisteria in the villages, the vineyards no longer fields of sticks but leafy green and lovely. Starting SJPP in May you might still catch some of the wheat/barley fields now quite high as well as blooming roses planted on the vineyards to attract pollinating bees but the wildflowers will be gone the fruit trees past blooming everything still green but monochromic, town and village gardens still pleasant, the weather not yet summer but walking in 30 degrees is not much fun. I best enjoy starting the week after an early Easter, nice and cool easy for walking, the holiday crowds have diminished, the Camino is in full bloom in and especially out of the towns, and even the meseta is green. In my experience, nature can make or break a Camino, the Via di Francesco, or the bits of the Via Francigena which I have walked..