Wait until age 9–12 months when your baby holds their head steady and sits...

https://www.bookmark-friend.win/wait-until-your-child-turns-one-and-sits-up-unsupported-confirm-they-hold

Wait until age 9–12 months when your baby holds their head steady and sits upright unassisted. Choose front seats for connection, rear seats for long-term growth, or trailers for maximum stability. Always pick a well-fitted helmet for every ride.