Dear Will,

I agree that you should wait until there is some brood in the upper box
before you place the excluder.  My experience is that some colonies will
go through an excluder no matter what.  Most, however, need some
inticement to go through, and brood is the best.  Just make sure the
queen is below when you add the excluder.  Once they have started going
through the excluder there seems to be no problem.

Jerry in PA.