You can use a sling with a baby from day one. It takes a little practice to get the hang of using a sling, but with some practice you will soon find that you can put baby in a sling quickly.
Stretchy wraps are often used with newborns because they are easy to use and the stretch of the wrap molds to the baby. With a stretchy wrap, like a Moby or Sleepy Wrap, you tie it on in one basic way and use this same tie to carry your baby upright or cradle style. You can also carry your baby in a semi-cradle style, where the baby is laying almost in a sitting position sideways in the wrap. I’ve always found it easier to tie on the wrap at the beginning of my day and leave it on throughout the day. I then just put baby in and out of it as needed. This way, I am not needing to retie the wrap multiple times a day. When you have a newborn, anything that makes your life easier is key. A woven wrap can also be used with a newborn and all the above would apply.
Another carrier I suggest for newborns is a Sakura Bloom ring sling. A ring sling is adjustable and so can be adjusted to fit comfortably and tightly around your baby for full support. It’s a one shoulder carrier and is quite easy to put it on and off throughout the day. Baby can lay cradle or upright in a ring sling and most mothers are able to nurse with baby in the ring sling. The tail of the ring sling comes in very handy when using it for a newborn, as it can be used as a burp cloth, cover for nursing, and the pocket can be used to hold your small items.
You should always be careful to use correct positioning when using a carrier, but this is particularly important when wearing a newborn.