If he looks like he's got sausage butt, then he will probably poop soon.
I don't keep track of my BPs' bowel movements, but they seem to go at least once a month or two if they're eating regularly. Mine usually poo when they shed.
If it looks like he's constipated, you can soak him in warm water if you really want to. Warm water and a gentle massage around the hind quarters usually does the trick.
But with that said, I honestly won't worry about it. He's probably fine and will go soon.