inoculating a new bag during s2b transfer

Is it possible to drop colonized Uncle Ben's into a new bag of Uncle Ben's during the transfer to bulk substrate step? Will it reduce the time needed to firm up a new bag of rice, or is it about the same time as fresh spores?

Also, is it possible to wait too long before going bulk? If i inoculate a second set of bags before going bulk, might they go bad before my first set has finished flushing?