Wait until your baby sits up independently, usually around 12 months, so they...

https://highstylife.com/can-i-use-a-child-bike-seat-on-an-e-bike-a-service-writers-guide-to-family-cycling/

Wait until your baby sits up independently, usually around 12 months, so they can support a helmet. Front seats suit smaller riders, while rear racks handle older toddlers well