You don't need to change A/T Transmission Fluid at 40k. That's for sure. Not before 70k. Usually, ATF's lasts around 100k easily unless you are driving very harshly. Just check the transmission fluid color, if it is pinkish on white tissue, you are all good. Get it changed around 70k.
As per the manual, it says change after 150k which I don't trust. I will get my A/T Fluid changed when I get the chance. I just bought the car used so just to be on the safe side. Although the color of my fluid is still kinda pinkish.
Here is the picture from manual