Thank you for your email,There is no problem with using the mill without running aliitle grain through and discarding the grain.We do recommend that you do that, but there will be nothing in your beer that will kill you or even worse make the beer taste bad.
We recommend running alittle grain through the mill just to remove and impurities like dust or small flakes from knurling the rollers. But lately no mill has sat around here long enough to collect any dust and we do clean the rollers before we assemble the mill, So I don't see any problems with using the first batch you have ran through the Barley Crusher.
If there is anything else I can do for you please email me
Thank you
Randy
NB C Products Enterprises Inc.