Wait until your baby reaches the 9-12 month mark to start biking. They must...
https://echo-wiki.win/index.php/What_is_Safer_on_a_Busy_Street:_Trailer_or_Rear_Seat%3F
Wait until your baby reaches the 9-12 month mark to start biking. They must hold their head up steadily while wearing a helmet and sit unsupported