Ben Simmons could get back on the floor sooner than expected. Or maybe that was the plan all along. Ahead of tip-off in the Nets’ regular-season finale against the Indiana Pacers on Sunday, Simmons participated in pregame warmups for the first time since arriving in Brooklyn. And there’s increased optimism Simmons could make his debut in the Nets’ first-round playoff series if his lower back continues to strengthen without a setback, The Athletic reported. Simmons did some light running and went through a variety of shooting drills. In those drills, he used crossover combinations and got signi…