I am team 'early spring'. The plumeria start waking up here around the end of February and I then start a mad regimen of fertilizing. By the end of March we may see our first blooms.
Having said that, our 'winter' is the time when we can be most active in the yard and so I usually undertake a big project. Two years ago we built a pergola, last year we made shell paths, and this year I am working on creating a new succulent garden in one of my beds. The cooler days mean I can spend a lot more time outside without keeling over from the excessive heat in the summer.