I will have a newborn and a 20 month old, I have a double pram but I plan on using a sling for the newborn on walks/popping to the shop etc I had a normal structured carrier for my current DD but I found it too structured and uncomfortable (could be because I only used it when DD was 5+ months). I like the look of the wrap ones, looking for recommendations please. Also is there a time limit on how long a newborn can be in them?