I have mine at the end of my chain. I do this for a few reasons. First, I have some fuzzes on my board and they don't sound good at all if there is anything buffered in front of them. Secondly, the buffer just sounded the best at the end of my chain. It seemed to help the high end the most in this position.
I use it as a clean boost...pedal volume up, pedal gain way down (7-8 oclock)...right now its at the beginning but im gonna try the end...the idea was to boost the signal at the beginning to send it through my pedalboard...I have a barber launch pad at the end of the chain to increase volume