Hello,
I have felt really good after using BSFF for like 20 min. I read a book about on how to always have an excuse ready when somebody tries to manipulate you, and so after almost every sentence I read I picked up a negative belief about myself that I then cleared. And it was while I was in a diner so I said all of the sentences and my cue word in my head. After reading and using BSFF for 20 min I felt tingling body sensations all over my body and just couldn't stop smiling and laughing any more, so I quickly got out of the place not to start laughing about how funny the whole world is

Although the euphoria didn't last for a long time, I did feel really good and noticed energy running all over my body while doing it.
Plus, while actually doing it I was drinking a cup of Latte (some strong coffee) and then yawning the entire process. But it felt really good, the energy and all.
So, my conclusion?
A great time to do any work on your negative beliefs might be while reading a self-help book, which usually brings forth MANY unpleasant feelings and memories in most of us (at least that is my experience, yours may be different). Also, be prepared to yawn A LOT when doing BSFF

Cheers,
Arkazor