There's no set "schedule"... He'll go when he's ready to go... Usually when sheds are upcomming, you'll notice that your bp won't deficate UNTIL the shed... other than that, it could be every week, or it could be every month... Even if he gets into a "routine" though, and he misses a couple in a row, that doesn't mean he's in any trouble, or sick.

I find that with the 31 that I have, if I clean cages on Wednesday, they usually leave me a nice present on Thursday.

Hope this helps..