Mix yeast, warm water, and 1/4 cup flour until smooth in a small bowl; set in a pan of lukewarm water (water should come 1/3 of the way up sides of bowl) and let stand in a warm spot until bubbles form on yeast mixture, 5 to 10 minutes.Meanwhile, sift 3 cups flour with the sugar and salt and set aside.Cream butter in a large bowl with an electric mixer until fluffy. Add flour mixture, a little at a time, alternately with eggs, Beat 2 minutes at medium speed. Add yeast mixture, beat 1/2 minute at low speed, then 2 minutes at medium speed. Add remaining 3/4 cup of flour by hand, a little at a time, beating with a wooden spoon after each addition. Cover dough with cloth, set in a warm, draft free place and let rise until doubled in bulk, 2 1/2 to 3 hours. Stir dough down, cover with foil, and refrigerate 6 to 8 hours or overnight.Now divide dough, shape into 24 brioches, allow to rise. About 15 minutes before you’re ready to bake, preheat the oven to 425 F; set rack in lower 1/3 of oven. Gently brush brioches with glaze. Place on baking sheets and bake 12 to 15 minutes until well browned.