These are the frames that you're looking for when you're timing your run.

Timing starts when you press 'Start Game'. The frame on the left shows the main menu before pressing START, and the frame on the right shows it one frame after START has been pressed. The FIRST frame of the run shows Buzz's hand on the left side, and the yellow arrow is almost touching the 'S' in 'Start' (arrow position varies a little).

Timing stops the same frame that you can see the car blinker on Andy's mom's car, which will be the LAST frame of the run. Note that the frame on the left is only for the sake of comparison, the right frame is the correct frame. Buzz and Woody will start moving towards the car automatically after that frame (control is lost).

Side-note: Make sure to turn off 'Storyline' in Options, as it will add a lot of time to your run. You only need to do this once after boot-up. If you reset the options will be kept, but if you power-off, they will be lost.