C.A.
I put my daughter in the shopping cart once she outgrew the carrier, around 6 months. What I did was prop her up with the diaper bag on one side of her and my purse on the other. She wasn't sitting up, but she did have great head control at that time and just kind of leaned on one of the two bags. The first time, we just cruised around the store, we didn't do any shopping, just incase she didn't like it.