My girl is 5 months today and she’s also in the pram seat because of this exact reason. Our pram seat does go flat so can be used from birth but she is loving life now she can nosey around
What pram do you have? Lots of them are suitable from birth. If it lies flat then it's fine to use. We have him sitting up a bit on the middle setting and then lie him down once he's asleep
My girl is 14lb and she goes it the big seat x
My girl has just turned 5 months and I've moved her to pram seat. I'd say it depends on their strength and stability. I have her slightly reclined still though as don't want too much stress on her spine