Wait until your baby sits independently with a steady head, usually by age one....

https://www.oscarbookmarks.win/wait-until-your-baby-holds-their-head-steady-independently-usually-around-9-12

Wait until your baby sits independently with a steady head, usually by age one. Choose front mounts for interaction, rear seats for stability, or trailers for reclining safety. Always confirm neck strength first. Helmets are non-negotiable every ride!