I used to grow in containers in Houston and now grow in the ground just north of Austin. In both instances, most trees would leaf out within a three week period. Where I am now, all of my trees die back just about to the ground in the winter. This makes it difficult to judge cold hardiness. Also, some come back from the stump just above the soil line, others come from below. There were times I wondered if a tree was dead when I needed to wait for it to break the soil surface.
Having said all that... this year, my MVSB (or is it MBVS?) was the first to show signs of breaking dormancy this year. It sent out a sucker (based on angle and distance from trunk) from about 1.5" below the soil line that broke the surface almost a month before anything else thought about waking up.
~james