Your opponent is about to strike. You then see the ball coming towards you at a good pace. Don’t panic. Don’t rush.
Track it as if you were going to catch it.
Don’t think about stroking yet.
Once the ball has bounced, observe it intently, now you are stroking it with some pace on your racquet, feeling the brush of the strings across the ball while you accelerate, and finishing the groundstroke all the way.