Interesting that where I am, in SW France, my sprouting broccoli had no signs of purple shoots three days ago. Then yesterday I checked again and all the plants were covered in the first visible shoots, no central head. but lots of shoots which we might treat ourselves to on Easter Day.
And our cavelo nero Kale has been shooting for a couple of weeks now! i pick these just like sp broccoli, before the flowers burst, and they are just as nice, really good cooked quickly in a wok.