Normally my newborn sessions are held within the first 2 weeks after birth. This is because babies are more sleepy and are happier to be moved and posed, dressed and undressed to get the desired shots. Rufus was 5 weeks old and is the oldest 'newborn' I have photographed. He took longer to settle, but once he did he was fast asleep. He didn't like the posed shots on the beanbag so instead we did a couple of different set ups in the basket as he was cocooned and nice and comfy there.
It was lovely taking pictures of him with his big brother - It's quite a challenge trying to get two year olds to sit still for long enough! But we managed to get a few lovely ones of them both, although his big brother much preferred posing on his own (and was very good at it!).