the volume pedal needs to be after a buffered, "active" signal, or it will suck tone.
once that is confirmed, it depends on what you want to use it for.
at the very end it'll be a master volume for the whole rig; before the drive or compression, turning the pedal down will clean up the sound as it's turned down, much like turning down the volume on the bass.
(as an aside, is this the 250k or 25k pedal? because the 250k after a buffer will tend to be really abrupt, not having a good sweep; 25k is best for after a buffer for that reason, and still won't hurt the sound.
frankly, given that the 250k sucks tone before a buffer and has a bad sweep after one, i don't even see the point of that pedal at all.)
Guitar Repair Gnome
Alpha Music, VA Beach