I was lucky enough to have a big fellow at home and so I didn't have to get the infant seat before starting with the convertible. The built in infant cushion worked just fine for our purposes by the time we actually left the house with him.Actually, I was doubly lucky because a friend bought this for me and I didn't have to pay for it. She bought it for me because she so strongly recommended it over all the other car seats out there... and the last time she used one was almost ten years ago, so I think the fact that she still remembered it is worth noting. The straps don't twist. That's the biggest thing she told me... and while I don't really have anything to compare it to, the straps don't twist... and my little guy seems comfortable and secure. That's enough for me.