Celtics big man Robert Williams hasn’t played since Dec. 6 due to a left hip injury. But in an interview Friday on 98.5 The Sports Hub’s “Toucher & Rich,” Celtics president of basketball operations Danny Ainge said Williams is on track to return in a little under a month. “Robert Williams is progressing,” Ainge said. “He was out working on the court (Thursday). He’s starting his transition back into all the live action, and we anticipate him being back with us somewhere in the neighborhood of March 1.”