Hi Gino, et al,
It's fine to experiment with your compressor placement; there's no hard rule as to what should go where in a signal chain. The "conventional wisdom" though, IF you're at all concerned with noise, is that anything in the chain before the compressor that creates "system noise" or anything else (Heaven help you if it's a distortion or overdrive!), will be exacerbated greatly and uncontrollably when it hits the compressor. IF that's effect you want, absolutely go for it, but it may also be a good way to empty a club or cost you a session! Just sayin'... (-:
Cheers,
Berington