To Specify the Frame Number at Which to Begin Using a Camera

Select the Script Camera tool.
Select the camera.
The Script Camera dialog opens.
In the Start Time field, enter the time, or the number of the frame, to begin using the camera.
From the Interpolation option menu, choose the interpolation method — Linear or Spline — for the transition to the camera.
From the Velocity option menu, choose the velocity type — Constant, Accelerate, Decelerate, Accelerate-Decelerate, or Infinite — for the transition to the camera.
Click the OK button.
The script entry is added to the list in the Animation Producer dialog.