I took DS to Costco when he was 3 days old. We went to buy a diaper bag, they didn't have them anymore, but we bought two nice recliner chairs.

Oh and he survived. Actually, when DS was 5 days old I went to work to pickup my paycheck. I took both of the kids, my boss was there and insisted that we all go out for lunch. I was freaking out, thinking what am I going to do if my 6yo starts misbehaving and my 5 day old starts crying.

It was a fancy restaurant, but they both did just fine.
It's also a well known fact that grandmothers have no idea what they are talking about.