Wait until your baby sits up confidently, usually by 12 months, with enough...

https://www./parenting/when-can-a-baby-go-in-a-bike-seat-an-age-by-age-guide/

Wait until your baby sits up confidently, usually by 12 months, with enough neck strength to support a helmet. Trailers offer the smoothest start. Front seats build engagement, while rear seats suit older toddlers. Always test the fit before riding.