what age can a baby/child go into a bike seat?

[LizzieHart]

I have a 6 month old DD and a very solid dutch bike with a child seat. When can the two meet safely? Also where is a good place to buy protective things like hat? Is there anything else I should get?

once babysit can sit up is usually fine,you can get helmets at most good bike shops,we got our lo a helmet at wilkos and it was only £5!!

DD went into a crossbar seat at 6 months.