You can restrict the range of time states that are considered when VisIt is performing a query over time if you specify a start or end time state in the Query Over Time Window. To set a starting time state, click the Starting timestep check box and enter a new time state into the adjacent text field. To set an ending time state, click the Ending timestep check box and enter a new ending time state into the adjacent text field.
In addition to setting the starting and ending time states, you can also specify a stride so VisIt can skip frames in the middle and consider every Nth frame instead of every frame. If you want to specify a stride, enter a new stride into the Stride text field in the Query Over Time Window and click the Apply button.