What is Neville Goddard’s “3 day rule”?

“If I could completely saturate my mind with one sensation and walk as though it were already a fact, I am promised (and I cannot find any denial of it in this great book) that I do not need more than a three day diet if I remain faithful to it. But I must be honest about it. If I Change my diet in the course of the day, I extend the time interval.”

“You ask me, “But how do I know about the interval?” You, yourself determine the interval.”

“The Bible gives it as three days; the duration is three days for response in this world. If I would now assume I am what I want to be, and if I am faithful to it and walk as though I were, the very longest stretch given for its realization is three days.”

“Now, how long it takes for what I have heard him say to come to pass, I don't know. As we tell you in that story of the book of Habakkuk, the vision has its own appointed hour. It ripens. It will flower. If it be long, then wait, for it is sure, and it will not be late. So one seed grows overnight. Another seed takes a month. Another seed takes a year. As in birth, a boy, a child comes to this world nine months, but a chicken comes out in 21 days. And so everything has a different interval of time between conception and birth in this world. So what determines the nature of that interval, I don't know.”