It's funny, I get this question all the time, and I never would have said "G."
Is the answer:
A. As soon as you find out you're going to have a kid, so you can get used to opening the damn things.
B. By the time the kid is born.
C. By the time the kid starts crawling.
D. By the time the kid starts walking.
E. A few months after you buy them, so they can have a chance to get acclimate to your kitchen space.
F. After the tenth time your wife says don't worry about it, she's going to install them herself, you just go to the gym.
G. Three minutes after turning the corner into the kitchen and seeing your one-year-old daughter playing happily with a bottle of laundry detergent and snuggling a plastic grocery bag.