How long do they need to lie flat for?

We've got a stroller which you can adjust to flat up to sitting up. I just wondered, how long does the baby need to lie flat for?

I reckon you'll know when it's best to sit bub up. I started sitting Nina up in her pram from 5 weeks, sitting up half way, and she has been sitting upright since about 4 months.

I started putting Charlies half way up at around 2 months old. He's 4 months now and still like that because if i put it up and more he keeps rolling to the side.

Cool, thanks - he probably won't be going in the stroller all that much to begin with anyway, but I just wondered!

I have heard that you should wait till up to 6 months as it is bad for their backs to prop them up before they are ready, but then again some babies can sit on their own by then anyway!
I think when Aidyn was about 3 months I would put the pram on the halfway propped up setting.

I didn't prop Milo up in his pram unitl he was holding his own head up by himself, and I never put it all the way to the sitting postition until he was sitting on his own.