How come when Dio stops time Jotaro can move but Dio can't when Jotaro stops time? In JoJo's Bizarre Adventure, Jotaro seems able to move even while Dio stops the time. On the other hand, Dio can't when Jotaro stops the time.

Why?
Jotaro planned to stop time when the limit of DIO's time stop was finishing.
This happened when Jotaro did the finishing blow after he survived the road roller attack.
And when DIO stopped time, Jotaro can't use the ability but can feel the situation in this case of &quot;time stop world&quot;, but when he can move, Jotaro can trigger the ability while he is in DIO's stopped time by use his time limit between DIO's stopped time and the end of it triggering.
He basically counters DIO's stopped time.