By Eric Pierce
& Mike Ward
Staff Writers

Although formal completion of the SBC Warburg Dillon Read/UBS Securities merger is slated for early May, the game of musical chairs has started. Thursday will be a critical day: that's when bonus checks for 1997 performance should clear employee bank accounts at both firms. Savvy firm-hopping Wall Streeters typically wait to clean out their desks until the bonus money is in their hands.