Wait until your baby sits up independently, usually around 9 to 12 months....

https://www.mediafire.com/file/7o6fhycs59kemfn/pdf-41704-93589.pdf/file

Wait until your baby sits up independently, usually around 9 to 12 months. Always ensure they support their own head under a helmet. Front seats offer great interaction, rear seats feel secure, and trailers allow for comfy naps