In this case, it wasn't about regurging, or time - it was that the snake was not eating, and otherwise indicating stress.
Often, experienced keepers such as myself, or others that often find themselves helping new owners who continually run into the same sort of issue, we develop a rule of thumb to help ourselves and new owners know when to try and start handling their new pets for the first time. Me, I prefer to wait at least two consecutive feedings to ensure that the snake is fully settled in and no longer stressed. Some keepers prefer a month, regardless of feeder behavior, others feel that if it eats once, no big deal.
The point is that the issue here was that the animal was stressed and showing it the only way it could - by not eating. So we emphasize the whole "Don't touch it yet" thing to help hammer home that most ball pythons do not tolerate lots of handling right away, and refusing to eat is one way they tell their keepers they are stressed.
-Jen