Does anyone know at what age (or weight) to take these inserts out? The car seat is 4-120 pounds and I want to switch my 9 month old (20lbs) to this car seat from his infant one. He kinda fits awkward in it so I was wondering if I’m supposed to take them out or keep them in until he’s older. I read the instructions that came with it and it just said what it was, it did t say how long to keep it in for