In some cases the probiotics take hold pretty quickly, while in others they may need a few days to really gain a foothold in there. I'd say be on the lookout another day or two, maybe three at most, to see some real changes from them. Nat's room-clearing farts as a baby disappeared after only a day, but now the kids are older and their school gives them stuff I wish they wouldn't, they're on daily probiotics for maintenance anyway. And we double up during and for about 7-10 days after a course of A/B's.