Wow, our thermals work very different. Perhaps it's the shape of our ridges, being long, narrow hog-backed ridges? Our thermals are running downhill until the sun peaks over the horizon (in fact, even before that). Once the sun hits the tops of the trees, the air there warms and starts to rise. This draws the air from below (down along the ridgetop) upwards. So our rising thermals start as soon as the sun hits the treetops.
On a calm morning, when hunting the ridgetops, the air is going straight up starting just after first full daylight.