Most babies are ready for bike travel around 12 months, though neck strength is...

https://romeo-wiki.win/index.php/Do_I_Need_to_Avoid_Curbs_with_a_Baby_in_a_Bike_Seat%3F_The_Mechanic%E2%80%99s_Guide_to_Smooth_Riding

Most babies are ready for bike travel around 12 months, though neck strength is your true north. Your little one must sit unsupported and hold their head up steadily while wearing a helmet