I've handled snakes after 1 or 2 feedings but that's because I sometimes lack patience and discipline. I agree that it's best to wait until they've eaten 3 times for you. The less stress for the snake the better.
I have handled prior to 3 feedings as well, but as experienced keepers we know what to look for in our snake's behaviors.
I think it's best for new keepers to wait it out though.