was shooting outdoors around 8am and i had to constantly change my white balance because of the sun.
there are many things you can white balance off if you choose to use custom white balance. some like to use a plain piece of white paper, white or grey cards, and i have even successfully white balanced off the sidewalk. i like to use a grey card when i can because it not only is (neutral) 18% grey but it gives me a warmer tone than balancing off white.
if you’re shooting video i highly discourage you from using auto white balance. auto does an okay job, however, since lighting is always changing 